Chest drainage systems and methods

ABSTRACT

A chest drainage system includes a collection device and a fluid pathway configured to extend from the collection device to a patient. A pressure source is configured to selectively provide sub-atmospheric pressure to the fluid pathway. The system is configured to introduce sub-atmospheric pressure from the pressure source at a substantially constant target pressure and at a dynamic pressure that varies from the target pressure. A method is also disclosed for draining a pleural cavity of a patient. The method involves applying dynamic pressure to the pleural cavity of a patient by changing sub-atmospheric pressure applied to the patient such that the patient&#39;s pleura moves without any or limited patient activity, thus facilitating removal of loculated fluid from the pleural cavity. The method may involve the use of the chest drain system.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalPatent Application No. 61/856,427, filed Jul. 19, 2013, the content ofwhich is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The field of the invention relates generally to medical drainagesystems, and more particularly to chest drainage systems.

BACKGROUND OF THE INVENTION

A number of fluid recovery systems have been developed for drainingfluid, such as air and/or blood, from a patient. An example of such afluid recovery system is a chest drainage system. Chest drainage systemsare intended to remove fluid from the pleural space or the mediastinalcavity and to restore the sub-atmospheric pressure that is normallypresent in the pleural space. The systems are usually adapted to allowsuction to be applied to the chest cavity to facilitate, among otherthings, the removal of fluid from the pleural space. Once the fluid hasbeen removed, the pleural cavity is allowed to heal and the normalsub-atmospheric condition of the pleural space is restored.

Over the years, various drainage systems have been proposed. Forexample, U.S. Pat. No. 4,605,400 discloses a surgical draining apparatushaving an air leak indicating means for indicating the directional flowof any gases through a passageway and optionally the qualitativequantity of these gases. The air leak indicating means includes a liquidtrap which is visible through the container. Thus as any gases flowtherethrough, bubbles are formed which serve as visible indicators ofsuch a flow and of a patient air leak. No bubbling through the liquidindicates a proper operation of the drainage apparatus. However,continuous bubbling through the liquid indicates either an air leak inthe connections or an air leak in the pleural cavity of the patient. Thegases pass through an aperture which is uppermost in a slanted dividermember. However, as the flow of gases increases, the gases additionallyflow through succeeding lower apertures along the length of the dividermember. Thus, the lowermost of the apertures through which the gasesbubble indicates the volume of flow through the air leak indicatingmeans. Suitable indicia are provided on the outside of the drainageapparatus to indicate this to the user.

U.S. Pat. No. 4,654,029 discloses an electronic drainage systemincluding a combination of electronic and mechanical components formeasuring and displaying values for air flow, suction, patientnegativity and maximum negativity. A patient air flow transducer islocated to measure the flow rate of air and other gases in a conduitfrom the patient. A signal processor is electrically connected to thetransducer to convert the signal from the transducer to a form needed byan air flow display. The readout of the display can be provided in unitsof liters per minute. A patient negativity transducer is also providedin the air conduit to measure the negative pressure in the pleuralspace. Since larger levels of negativity may occur while an attendantmonitoring the system is away from the patient, it may be useful for thephysician to know what maximum level of negative pressure was actuallyattained (e.g., if the tube inserted into the pleural space becomesclogged with blood clots, damaged tissue or the like). In order to cleara blockage, the attendant “milks” the tube in an attempt to reopen it,however, this procedure often causes high values of momentary negativityon the patient. In order to determine that this has happened and to whatextent, a maximum negativity hold device is electrically connected tothe signal processor and is so devised as to record and store negativityvalues up to the level permitted by an excessive negativity release orsafety valve. The stored value is displayed on a display function. Also,a weight transducer is electronically connected with a fluid collectionchamber for weighing the fluid in the chamber as a function of time. Theweight transducer and an associated processor and display, enable themeasurement and recording of the parameter fluid versus time.

U.S. Pat. No. 4,740,202 relates to a portable suction system in whichthe vacuum for suction purposes is provided by evacuating a rigidplastic chamber connected to a vacuum pump. A disposable bag is affixedto a suction port on the chamber's cap. In operation, the rigid chamberis evacuated by the vacuum pump, thus drawing air and fluids through asuction tip into a suction port and into the flexible collection bagwhere the liquids are retained for collection.

In U.S. Pat. No. 6,352,525, an entire drainage system is made completelyportable by combining a vacuum pump, a power source, a vacuum chamber,and a collection unit into a single unit. A vacuum chamber, vacuum pumphousing, and collection reservoir are removably connected to the chesttube drainage system, each component of the drainage system beinggenerally disposable. A flow meter is interposed between the vacuumchamber and the vacuum pump housing to indicate the amount of air flow.The flow meter includes a flow meter tube within which a floating ballrests. The diameter of the floating ball, the weight of the floatingball, and the inner diameter of the flow meter tube are configured suchthat the floating ball rests substantially near the bottom of the flowmeter tube when there is little or no leak from a patient's lung(s), andsuch that the floating ball rests substantially near the top of the flowmeter tube when a substantial leak exists in a patient's lung(s). In thecontext of a patient recovering from lung-related surgery, the flowmeter indicates an amount of air leak from the patient's lung(s). Theamount of air flow through a chest tube is indicated by the flow meter,and a practitioner may adjust a potentiometer until flow characteristicsindicated by the flow meter correspond favorably to an amount of airleak which may persist for some time at a lung.

U.S. Pat. No. 7,207,946 discloses a method of providing a signalindicating information related to air evacuation from a chest cavity. Anair escapement conduit is inserted into an air evacuation pathwaybetween the chest cavity and a vacuum source, allowing an air flow inresponse to a pressure differential, generating a signal related to theair flow, and indicating air evacuation information in response to thesignal. The air escapement conduit includes a bubble chamber having afluid disposed between an inlet port and an outlet port so that airflowing between the ports flows through the fluid and forms bubbles.Bubbles in the fluid are counted and a bubble detection signal relatedto counted bubbles is generated. A difference in air pressure betweenthe ports is detected, and a signal related to the difference isgenerated. A flash of light provided by a light emitting diode indicateswhen the air evacuated per selected unit of time exceeds a predeterminedlevel. Data representative of the signal may be stored.

Despite many developments in the field of fluid drainage, however, thereremains a need for improved drainage systems, particularly improvedchest drainage systems.

SUMMARY OF THE INVENTION

A chest drainage system according to an example embodiment of thepresent invention includes a collection device, a fluid pathwayconfigured to extend from the collection device to a patient, and apressure source configured to selectively provide sub-atmosphericpressure to the fluid pathway. The system is configured to introduce thesub-atmospheric pressure from the pressure source at a substantiallyconstant target pressure and at a dynamic pressure that varies from thetarget pressure.

According to an example embodiment, the constant target pressure isselected for the patient.

According to yet another example embodiment, the chest drainage systemhas a target pressure is −20 cm H2O.

According to another example embodiment, the chest drainage system has acontroller configured to maintain the target pressure and apply thedynamic pressure.

According to an example embodiment, the chest drainage system comprisesan internal vacuum pump configured to adjust the sub-atmosphericpressure.

In another embodiment, the chest drainage system has an accumulatorconfigured to adjust the sub-atmospheric pressure.

According to an example embodiment, the chest drainage system has a ventvalve configured to adjust the sub-atmospheric pressure.

In another embodiment, the chest drainage system is configured to applydynamic pressure by changing the pressure applied to the patient suchthat the patient's pleura moves without any or limited patient activity.

According to an example embodiment, the chest drainage system has acontroller programmed with a computer algorithm that varies thesub-atmospheric pressure according to a predetermined pressure profileor pattern.

A chest drainage system according to an example embodiment of thepresent invention includes a collection device, a fluid pathwayconfigured to extend from the collection device to a patient, a pressuresource configured to selectively provide sub-atmospheric pressure to thefluid pathway, and a controller programmed with a computer algorithmthat varies the sub-atmospheric pressure according to a predeterminedpressure profile or pattern. The system may be configured to introducethe sub-atmospheric pressure from the pressure source at a substantiallyconstant target pressure and at a dynamic pressure that varies from thetarget pressure. The system may further be configured to apply dynamicpressure by changing the sub-atmospheric pressure applied to the patientsuch that the patient's pleura moves without any or limited patientactivity.

According to an example embodiment, the constant target pressure isselected based on the patient.

An example method for draining a pleural cavity of a patient accordingto the present invention comprises a step of applying dynamic pressureto the pleural cavity by changing sub-atmospheric pressure applied tothe patient such that the patient's pleura moves without any or limitedpatient activity, thus facilitating removal of loculated fluid from thepleural cavity.

According to an example embodiment, a negative pressure scheme orsetting is prescribed.

In another embodiment, the step of applying dynamic pressure comprises adecreasing pressure regimen, scheme or routine.

According to an example embodiment, the method further includes steps ofapplying (i) a brief increase in negative pleural pressure, (ii) a briefdecrease in negative pleural pressure to atmospheric pressure, and/or(iii) a return to the prescribed negative pressure after a previousvariation in pressure.

In another embodiment, the method further includes a step of controllingdynamic pressure using a computer algorithm and a step of varyingpressure according to a predetermined pressure profile or pattern.

According to another embodiment, the method further includes a step ofreducing patient pressure slowly toward atmospheric pressure when no airleak is detected.

According to an example embodiment, the method includes a step ofresetting patient pressure to the prescribed negative pressure upondetection of an air leak and/or fluid removal.

According to an example embodiment, the method further includes a stepof establishing additional sub-atmospheric pressure to the pleuralcavity upon detection of an air leak and/or fluid removal as detected bya chest drainage system, wherein the chest drainage system comprises acollection device configured to (i) detect air leakage and/or (ii) fluidreceived in (a) the collection device or (b) any tubing or conduit influid communication between the collection device and the pleural cavityof the patient.

According to an example embodiment, the method further includes varyingpressure according to a continuous wave pattern with a root mean squarevalue equal to the prescribed negative pressure.

According to another example embodiment, the method includes a step ofvarying pressure to include sudden changes in the prescribed negativepressure.

According to an example embodiment, the method further includes steps ofconfiguring patient settings, applying a target pressure to the pleuralcavity of the patient, applying a dynamic pressure in a waveform aroundthe target pressure, and returning the pressure applied by the system tothe target pressure.

According to another example embodiment, the method includes operatingan algorithm based on inputs including at least one of an initialpatient pressure, a fluid drainage hold time, and a percentagereduction. The method also may include applying a target pressure to thepatient, monitoring for fluid drainage; and reducing applied patientpressure by a percentage reduction of the target pressure if no fluiddrainage is detected.

According to another embodiment of the present invention, the dynamicpressure comprises at least one of the following changes or patterns:(i) a bipolar pulse that interrupts a substantially constant appliedpressure, (ii) a pulsed sine wave that interrupts a substantiallyconstant applied pressure, (iii) a substantially continuous sine wave,(iv) a repeating square wave, and (v) a decreasing pressure pattern thatinterrupts a substantially constant applied pressure.

According to another embodiment, the method further includes the step ofsetting target patient applied pressure and superimposing a waveform orpattern of pressure upon the patient applied pressure setting, thewaveform or pattern including at least one of (i) a square wave, (ii) asine wave, (iii) a triangular wave, (iv) a saw-tooth wave, (v) a bipolarpattern, (vi) a unipolar pattern, (vii) a waveform, (viii) anypermutation of the foregoing waveform or patters (i) through (viii),(ix) a pattern that is changed upon user selection, or (x) a waveform orpattern optionally changed automatically based upon detected patientstatus.

In another example embodiment, the method includes the steps of settinga target patient applied pressure, monitoring for fluid drainage,decreasing patient applied pressure toward atmospheric pressure by setpressure intervals at set time intervals, and optionally returningpressure to the target patient applied pressure.

In another example embodiment, the step of returning pressure to thetarget patient applied pressure occurs.

According to an example embodiment, the method further includes thesteps of setting a target patient applied pressure, monitoring for fluiddrainage, decreasing patient applied pressure toward atmosphericpressure by set pressure intervals at set time intervals, andmaintaining the pressure at the target patient applied pressureirrespective of any detection of fluid drainage occurring resulting fromthe step of monitoring for fluid drainage.

A chest drainage system according to an example embodiment of thepresent invention comprises a collection device, a fluid pathwayconfigured to extend from the collection device to a patient andestablish fluidic communication with the patient's pleural space, and apressure source capable of being adjusted to provide sub-atmosphericpressure to the fluid pathway. The pressure of the fluid pathway ismanaged (i) during a first period to be at or within a predeterminedsub-atmospheric target pressure or target pressure range, and (ii)during a second period at least intermittently outside of the firstsub-atmospheric pressure range.

According to an example embodiment, the pressure of the fluid pathway ismanaged to enhance removal of any loculated fluid from the pleural spaceof the patient by intermittently changing the pressure applied to thepleural space.

According to another example embodiment, the system is configured toenhance removal of any loculated fluid from the pleural space of thepatient by intermittently changing pressure applied to the pleural spaceto sub-atmospheric pressure values that are outside of a target range ofsub-atmospheric pressure values.

According to yet another embodiment, the pressure of the fluid pathwayis managed to decrease applied suction in the pleural space of thepatient by reducing the applied pressure.

According to another embodiment, the chest drainage system is configuredto re-establish applied suction upon detection of a leak.

In another example embodiment, the chest drainage system is configured(i) not re-establish applied suction upon or resulting from detection ofa leak, and/or (ii) bypass or override via a user input or userconfigurable setting any configuration that otherwise would re-establishapplied suction upon detection of a leak. In the present examples, forinstance, the patient may be “weaned” off of any suction procedureirrespective of encountering events that otherwise would re-establishsuction.

In another embodiment, a chest drainage system includes a collectiondevice; a fluid pathway configured to extend from the collection deviceto a patient; a pressure source configured to selectively providesub-atmospheric pressure to the fluid pathway; and a controllerprogrammed with a computer algorithm that varies the sub-atmosphericpressure according to a predetermined pressure profile or pattern;wherein the system is configured to introduce the sub-atmosphericpressure from the pressure source at a substantially constant targetpressure selected for the patient and at a dynamic pressure that variesfrom the target pressure; and wherein the system is configured to applydynamic pressure by changing the sub-atmospheric pressure applied to thepatient such that the patient's pleura moves without any or limitedpatient activity.

In another embodiment, a method for draining a pleural space of apatient includes applying dynamic pressure to the pleural cavity of thepatient by changing sub-atmospheric pressure applied to the patient suchthat the patient's pleura moves without any or limited patient activity,thus facilitating removal of loculated fluid from the pleural space.

In another embodiment, the chest drainage method of the previousembodiment includes applying the dynamic pressure by applying a briefincrease in negative pleural pressure, a brief decrease in negativepleural pressure to atmospheric pressure, and/or a return to prescribednegative pressure after a previous variation in pressure.

In another embodiment, the chest drainage method of any of the previousembodiments includes controlling dynamic pressure using a computeralgorithm and varying pressure according to a predetermined pressureprofile or pattern.

In another embodiment, the chest drainage method of any of the previousembodiments includes a step of reducing patient pressure slowly towardatmospheric pressure when no air leak is detected.

In another embodiment, the chest drainage method of any of the previousembodiments includes resetting a prescribed pressure upon detection ofan air leak and/or fluid removal.

In another embodiment, the chest drainage method of any of the previousembodiments includes varying pressure according to a continuous wavepattern with a root mean square value equal to a prescribed pressure.

In another embodiment, the chest drainage method of any of the previousembodiments includes varying pressure to include sudden changes inprescribed pressure.

In another embodiment, the chest drainage method of any of the previousembodiments includes configuring patient settings; applying a targetpressure to a pleural cavity of the patient; applying a dynamic pressurein a waveform around the target pressure; and returning the pressureapplied by the system to the target pressure.

In another embodiment, the chest drainage method of any of the previousembodiments includes a decreasing pressure regimen, the method includingoperating an algorithm based on inputs including at least one of aninitial patient pressure, a fluid drainage hold time, and a percentagereduction; applying a target pressure to the patient; monitoring forfluid drainage; and reducing applied patient pressure by a percentagereduction of the target pressure if no fluid drainage is detected.

In another embodiment, the chest drainage method of any of the previousembodiments includes a dynamic pressure having at least one of thefollowing changes or patterns: a bipolar pulse that interrupts asubstantially constant applied pressure; a pulsed sine wave thatinterrupts a substantially constant applied pressure; a substantiallycontinuous sine wave; a repeating square wave; and a decreasing pressurepattern that interrupts a substantially constant applied pressure.

In another embodiment, the chest drainage method of any of the previousembodiments includes setting target patient applied pressure andsuperimposing a waveform or pattern of pressure upon the patient appliedpressure setting, the waveform or pattern including at least one of asquare wave, a sine wave, a triangular wave, a saw-tooth wave, a bipolarpattern, a unipolar pattern, a waveform or pattern that is changed uponuser selection, or a waveform or pattern optionally changedautomatically based upon detected patient status.

In another embodiment, the chest drainage method of any of the previousembodiments includes setting a target patient applied pressure;monitoring for fluid drainage; decreasing patient applied pressuretoward atmospheric pressure by set pressure intervals at set timeintervals; and optionally returning pressure to the target patientapplied pressure.

In another embodiment, a chest drainage system includes a collectiondevice; a fluid pathway configured to extend from the collection deviceto a patient; and a pressure source capable of being adjusted to providesub-atmospheric pressure to the fluid pathway; wherein pressure of thefluid pathway is managed (i) during a first period to be at or within apredetermined sub-atmospheric target pressure or target pressure range,and (ii) during a second period at least intermittently outside of thefirst sub-atmospheric pressure range.

In another embodiment, in the chest drainage system of any of theprevious embodiments, the pressure of the fluid pathway is managed toenhance removal of any loculated fluid from the pleural space of thepatient by intermittently changing the pressure applied to the pleuralspace.

In another embodiment, in the chest drainage system of any of theprevious embodiments, the system is configured to enhance removal of anyloculated fluid from the pleural space of the patient by intermittentlychanging pressure applied to the pleural space to sub-atmosphericpressure values that are outside of a target range of sub-atmosphericpressure values.

In another aspect of this invention, a chest drainage system isprovided. It includes a collection device and a fluid pathway configuredto extend from the collection device to a patient. The fluid pathway hasa proximal portion configured to extend proximally toward the patientand a distal portion configured to extend distally from the patient. Thechest drainage system also includes a pressure source configured toselectively provide sub-atmospheric pressure to the distal portion ofthe fluid pathway and a valve configured to selectively relieve pressurein the proximal portion of the fluid pathway. The pressure sourceincludes a pressure accumulator configured to store the sub-atmosphericpressure. The system is configured to open the valve and to introducethe sub-atmospheric pressure from the pressure source when apredetermined pressure differential is detected between the proximal anddistal portions of the fluid pathway.

According to another aspect, this invention provides a chest drainagesystem including a collection device and a fluid pathway configured toextend from the collection device to a patient. The fluid pathway has aproximal portion configured to extend proximally toward the patient anda distal portion configured to extend distally from the patient. Thechest drainage system also includes a sensor system configured to sensea pressure differential between the proximal and distal portions of thefluid pathway. A means is provided for substantially clearing a blockagein the fluid pathway between the proximal and distal portions of thefluid pathway, and a means is provided for determining when to actuatethe clearing means based on at least one of the pressure differentialsensed by the sensor system and an elapsed time of operation of thechest drainage system.

According to yet another aspect, this invention provides a chestdrainage system including a collection device configured to receivefluid from the pleural cavity of a patient. It also includes means fordetecting a pressure differential in the fluid collection system. Adisplay is configured to display a trend in occurrences of changes inpressure of the fluid pathway over time in predetermined time incrementsbased on a number of detections of pressure differentials that exceed apredetermined pressure differential during each of the predeterminedtime increments, the trend being correlative to the percentage of timethat the patient is deemed to have an air leak in the pleural cavity inthe predetermined time increments. The display is derived from a ratioof the quantity of time intervals, such as respiratory cycles of thepatient for example, for which the predetermined pressure differentialis detected (QRC_(leak)) in the predetermined time increments to thetotal quantity of time intervals (e.g., respiratory cycles of thepatient) in respective predetermined time increments (QRC_(total)).

According to still another aspect, this invention provides a chestdrainage system including a removable and/or replaceable collectioncanister having at least one inlet port and at least one outlet port; afluid pathway configured to extend from the at least one inlet port ofthe removable and/or replaceable collection canister to a patient; and areusable body portion having at least one inlet port releasably coupledto the at least one outlet port of the removable and/or replaceablecollection canister. The reusable body portion has a sensor fordetecting whether the at least one inlet port of the reusable bodyportion is coupled to the at least one outlet port of the removableand/or replaceable collection canister. The removable and/or replaceablecollection canister is configured to collect fluid via the fluid pathwayeither with or without suction applied when coupled to the reusable bodyportion, to automatically close the at least one outlet port of theremovable and/or replaceable collection canister and collect fluid viathe fluid pathway when uncoupled from the reusable body portion, and tobe alternated between gravity- and suction-based fluid collectionwithout interrupting a fluid connection between the patient and theremovable and/or replaceable collection canister or introducingatmospheric air into the fluid pathway.

According to yet another aspect of this invention, a fluid pathwayclearing apparatus is provided for a chest drainage system including acollection device and a fluid pathway configured to extend from apatient to the collection device. The fluid pathway has a proximalportion configured to extend proximally toward the patient and a distalportion configured to extend distally from the patient. The apparatusincludes an accumulator configured to store sub-atmospheric pressure andconfigured to be coupled to the chest drain system for providing thesub-atmospheric pressure to the distal portion of the fluid pathway. Italso includes a valve configured to be coupled to the proximal portionof the fluid pathway and configured to selectively relieve pressure inthe proximal portion of the fluid pathway.

In another aspect of the invention, a method is provided for clearing afluid pathway of a chest drainage system, the fluid pathway having aproximal portion configured to extend proximally toward the patient anda distal portion configured to extend distally from the patient. Themethod includes (1) detecting a difference in pressure having apredetermined magnitude between the proximal and distal portions of thefluid pathway; (2) opening a valve to permit release of pressure in theproximal portion of the fluid pathway; (3) introducing sub-atmosphericpressure to the distal portion of the fluid pathway from an accumulatorof a pressure source; (4) closing the valve; and (5) ceasing theintroduction of sub-atmospheric pressure to the distal portion of thefluid pathway.

In another aspect, the invention provides a chest drainage systemincluding a drainage catheter defining a drainage lumen and at least onedrainage opening through which fluid is drawn into the drainage lumenfrom a pleural cavity. The chest drainage system also includes a suctionsystem coupled to apply suction to the drainage lumen in order to drawfluid into the drainage lumen through the at least one drainage opening,the suction system including a pump, an accumulator in fluidcommunication with the pump, and a valve coupled between the accumulatorand the drainage catheter. The chest drainage system also includes afluid collector coupled to receive fluid from the drainage lumen of thedrainage catheter. The pump is configured to generate a negativepressure in the accumulator, the valve is configured to open when thereis a blockage between the pleural cavity and the fluid collector, andthe opening of the valve causes the negative pressure in the accumulatorto be applied to the drainage catheter such that the blockage is drawninto the fluid collector.

In another aspect, the invention provides a method for monitoring an airleak in a pleural cavity of a patient. The method includes the steps ofmeasuring a rate of pressure decay in the pleural cavity of the patient;correlating the rate of pressure decay to an associated air leak of thepleural cavity of the patient according to the following formula:

Q _(Airleak) α∫Pdt

where:

-   -   i. Q_(Airleak) is an extrapolated air leak    -   ii. P is a measured pressure    -   iii. t is time; and    -   iv. generating an indicator showing a trend in the magnitude of        the air leak of the pleural cavity.

In another aspect of the invention, a chest drainage system is providedthat includes a drainage catheter defining a drainage lumen and at leastone drainage opening through which fluid is drawn into the drainagelumen from a pleural cavity; a suction system coupled to apply suctionto the drainage lumen in order to draw fluid into the drainage lumenthrough the at least one drainage opening; and a fluid collector coupledto receive fluid from the drainage lumen of the drainage catheter. Italso includes a pressure sensor coupled to the suction system andpositioned for sensing a pressure in the pleural cavity; a processorcoupled to receive a signal from the pressure sensor based on the sensedpressure in the pleural cavity; and a plurality of indicators coupled tothe processor and configured to visually indicate a status correspondingto the sensed pressure in the pleural cavity to an operator. Theprocessor is configured to selectively activate the plurality ofindicators such that: a first indicator of the plurality of indicatorsis activated when the sensed pressure is within a first predefinedrange, a second indicator of the plurality of indicator is activatedwhen the sensed pressure is within a second predefined range, and athird indicator of the plurality of indicators is activated when thesensed pressure is within a third predefined range.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawings. It is emphasizedthat, according to common practice, the various features of the drawingsare not to scale. On the contrary, the dimensions of the variousfeatures are arbitrarily expanded or reduced for clarity. Included inthe drawings are the following figures:

FIG. 1 is a block diagram illustrating an exemplary chest drainagesystem in accordance with aspects of the present invention;

FIG. 2A is a schematic diagram illustrating another exemplary chestdrainage system in accordance with aspects of the present invention;

FIG. 2B is a schematic diagram illustrating an optional modification tothe chest drainage system of FIG. 2A;

FIGS. 3A-3E are schematic diagrams illustrating the operation of thechest drainage system of FIG. 2A;

FIG. 4 is a flow chart illustrating an exemplary algorithm for clearinga fluid pathway in accordance with aspects of the present invention.

FIGS. 5A-5D are images illustrating another exemplary chest drainagesystem in accordance with aspects of the present invention;

FIG. 6 illustrates another exemplary chest drainage system in accordancewith aspects of the present invention;

FIG. 7 is an image illustrating an exemplary display of the chestdrainage system of FIG. 6;

FIG. 8 is a graph illustrating measurements of the decay in pressure inthe pleural cavity of a patient as a function of time in accordance withan aspect of the present invention;

FIG. 9 is a graph illustrating the trend and rates of pressure decayrelating to an associated patient air leak as a function of time inaccordance with an aspect of the present invention;

FIG. 10 is a schematic diagram illustrating an exemplary arrangement ofelectrical components that can be used in a chest drainage system inaccordance with aspects of the present invention;

FIGS. 11A and 11B illustrate an exemplary tube set that can be used in achest drainage system in accordance with aspects of the presentinvention;

FIG. 12 is a flow chart illustrating an exemplary process for applyingdynamic pressure in accordance with aspects of the present invention;

FIG. 13 is a flow chart illustrating an exemplary process for applyingdecreasing dynamic pressure in accordance with aspects of the presentinvention; and

FIGS. 14A-14G are graphs illustrating exemplary dynamic pressure changesor patterns in accordance with aspects of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

This invention will now be described with reference to severalembodiments selected for illustration in the drawings. It will beappreciated that the scope and spirit of the invention are not limitedto the illustrated embodiments. It will further be appreciated that thedrawings are not rendered to any particular proportion or scale. Also,any dimensions referred to in the description of the illustratedembodiments are provided merely for the purpose of illustration. Theinvention is not limited to any particular dimensions, materials, orother details of the illustrated embodiments.

The exemplary systems and methods described herein are usable to drainor otherwise recover fluid from a patient. The systems and methods aredescribed herein primarily with respect to draining the pleural cavityof a patient or to chest drainage for convenience according toembodiments of the invention selected for description and illustration.However, it will be understood by one of ordinary skill in the art thatthe disclosed systems and methods are not so limited. The disclosedsystems and methods may be used to drain fluid from other body cavitiessuch as, for example, the cranial cavity or the peritoneal cavity.Accordingly, this invention applies to a wide variety of medicaldrainage systems, such as fluid recovery systems, including for examplechest drainage systems and those chest drainage systems used as pleuraldrainage systems.

Generally, chest drainage systems are configured to restore the lungsand pulmonary physiology to their normal condition, by removing airand/or other fluids to help re-establish normal vacuum pressures, lungexpansion, and breathing dynamics; to evacuate any pooling fluids and/orair following open heart surgery, thoracic surgery or chest trauma;and/or to facilitate collection of autologous blood from the patient'spleural cavity or mediastinal area for reinfusion purposes inpost-operative and trauma blood loss management. The disclosed systemsare usable by thoracic surgeons, cardiac surgeons, general surgeons,pulmonary physicians, oncologists, critical care physicians, nurses,home health care professionals, and other health care professionals.

As used herein, the term “patient” refers to an animal to be treated bythe disclosed systems and methods. While the systems and methods aredescribed herein primarily with respect to human patients, it will beunderstood by one of ordinary skill in the art that they are not solimited.

Referring now to the figures, FIG. 1 illustrates an exemplary chestdrainage system 100 in accordance with aspects of the present invention.System 100 is usable to drain fluid from the pleural cavity of apatient. As a general overview, system 100 includes a control module200, a collection device 300, and a fluid pathway 400 that is provided,for example, by a disposable tube set. Additional details of chestdrainage system 100 will be provided herein.

Control module 200 houses the electronic components that control chestdrainage system 100. Control module 200 is operable to collect and storedata about the operation of chest drainage system 100. Control module200 may be configured to receive power from an external power source(e.g., from an AC power source via AC/DC converter 202). Alternativelyor additionally, control module 200 may include an internal power source(e.g., a rechargeable battery). An internal power source may bepreferable to increase patient mobility with the chest drainage system100. Control module 200 may further include a switch, button, or otherdevice for powering control module 200 on and off.

In addition to electrical connection, control module 200 furtherprovides mechanical connections for use in the operation of chestdrainage system 100. Control module 200 includes a suction port 204 forreceiving suction from an external suction source (e.g., via connectionto a wall-mounted suction source). Control module 200 includes an airintake 206 for use in regulating the amount of suction applied by theexternal suction source. Control module 200 also includes a vent 208 forselectively providing communication with atmosphere. The use of thesemechanical connections in operation will be described in further detailherein.

Control module 200 allows the user to set the suction pressure appliedby the external suction source. For example, suction pressure may be setfrom approximately −5 cmH₂O to approximately −40 cmH₂O, with numericalincrements of the same or different pressure differentials, for exampleof intervals of 5 cm H₂O increments at −5 cmH₂O, −10 cmH₂O, −15 cmH₂O,−20 cmH₂O, −30 cmH₂O, and −40 cmH₂O. Control module 200 may also includean internal suction source for providing suction without an externalsuction source at, for example, −5, −10, −15, −20 cm H₂O. If the systemis set to a higher applied suction when the system is disconnected fromthe external suction source (e.g., to provide mobile suction), thesystem will automatically adjust the suction pressure to −20 cm H₂O.When control module 200 detects that an external suction source isattached, it may be operable to disable suction provided internally andoperate using the external suction source for applied suction. Controlmodule 200 may provide a visual notification to the user when suction isbeing provided internally.

Control module 200 further desirably includes an accessible USB port 210enabled to support automated system testing, diagnostics, and in-serviceupgrades. Where control module 200 includes a battery, control module200 may include a battery access port 212 to enable checking orreplacing the battery.

Collection device 300 receives fluid (e.g., gas or liquid or acombination of gas and liquid) drained from the patient. In an exemplaryembodiment, collection device 300 is a removable and/or replaceablecollection canister. In other words, it is optionally removable,replaceable, or removable and replaceable. Collection device 300includes an inlet port 302 for received fluid from fluid pathway 400.Collection device 300 further includes a suction port 304 for receivingthe suction pressure provided by control module 200. In this way,collection device 300 may be coupled to receive suction from controlmodule 200 and provide suction to fluid pathway 400. Like control module200, collection device 300 includes a vent port 306 for selectivelyproviding communication with atmosphere. The vent port 306 may becoupled to a relief valve in control module 200 for providing thecommunication with atmosphere.

Control module 200 may be operable to detect when collection device 300is full. When control module 200 detects that collection device 300 isfull or overflowing, it may provide a visual notification to the user.Chest drainage system 100 may further include a needle-less accessconnector to allow collected fluid to be withdrawn for testing andanalysis. A suitable needle-less access connector will be known to oneof ordinary skill in the art.

Collection device 300 may also desirably allow for the visual inspectionof collected fluid and have an access line to allow collected blood tobe withdrawn from the collection chamber for blood recovery, and allowthe trending of volume collected over time by providing a writeablesurface on the collection chamber to mark volumes at time increments. Inan exemplary embodiment, collection device 300 has a volume of at leastapproximately 1200 mL. When a chest drainage system is used forpediatric patients, it may be desirable that collection device 300 havea volume of no greater than approximately 200 mL.

Fluid pathway 400 provides a path for fluid from the patient to draininto collection device 300. In an exemplary embodiment, fluid pathway400 comprises one or more tubes. Fluid pathway 400 may include one tubefor draining fluid from the patient into collection device 300. Fluidpathway 400 may also include a second tube for selectively relievingnegative pressure in the first tube, as will be described below.Suitable tubes will be known to one of ordinary skill in the art fromthe description herein.

In operation, fluid pathway 400 is connected to collection device 300.Fluid pathway 400 may then be secured to the patient via a patient draincatheter inserted in the patient (e.g., via patient drain catheter 500).For suction drainage, control module 200 provides suction pressure tocollection device 300, thereby coupling the suction to fluid pathway400. For gravity drainage, gravity is allowed to draw the fluid throughfluid pathway 400 and into collection device 300. During operation,control module 200 may monitor and provide visual indications relatingto any air leak.

Control module 200 may preferably include a means for the user to mountit to a pole. For example, control module 200 may include hangers formounting. An exemplary hanger system is disclosed in U.S. Pat. No.7,232,105, which is incorporated herein by reference. Additionalstructures and equivalent structures for mounting control module 200 toa vertical pole or horizontal rail will be apparent to those of skill inthe art from the description herein.

Control module 200 may also include a handle. An exemplary ornamentaldesign of a handle system is disclosed in U.S. Pat. No. D517,897, whichis incorporated herein by reference.

During drainage of fluid from a patient, a dependent loop of tubing mayoccur when a portion of the tubing forms a U-shape that requires fluidin the tube to flow against gravity to reach the distal end of the tube.With drainage systems, gravity is an important factor affecting fluidflow into the collection device. Fluid collected in a dependent loop inthe drainage tubing can stop flow completely.

Accordingly, a chest drainage system according to aspects of thisinvention detects the state at which there is the presence of adependent loop. Then, the system applies more negative pressure to thefront (closer to the collection device) of the fluid trapped in thefluid pathway that is in a more distal portion of the fluid pathway,while allowing pressure to be relieved in the back (closer to thepatient) of the fluid trapped in the fluid pathway at a location that isin a more proximal portion of the fluid pathway. This creates a pressuredifferential that causes air and/or other fluids trapped in the tubingto move towards the sub-atmospheric pressure very rapidly in order tostabilize the system. For example, although the invention is not limitedto any specific time within which the system is stabilized or trappedfluid is removed, the pressure differential is preferably applied forless than 15 seconds, more preferably less than 5 seconds, and mostpreferably less than 2 seconds. It should be appreciated that thisamount of time is influenced by various factors including, for example,the magnitude of the pressure charge in the accumulator, the viscosityof fluid forming the blockage, the diameter of the drainage tube andother tubing of the system, any possible kinks or defects in the tubing,the amount of applied pressure, the volume of the blockage, and anyrestrictions attributable to the system connectors.

The negative pressure applied to the front or distal portion of thetubing may be created, e.g., through the utilization of a vacuum pump,to draw down the pressure in a pressure storage device such as apressure accumulator. While the accumulator is being charged withnegative pressure, it is isolated from the rest of the chest drain via avalve. The accumulator may optionally be a distinct, discrete componentfrom the rest of the drainage system, or may be an integral part of thedrainage system.

After a predetermined amount of negative pressure is achieved in theaccumulator, the valve may then be opened and the negative pressureexposed to the rest of the chest drain, and subsequently to the distalside of the fluid trapped in the tubing. In order to maximize themovement of fluid trapped in the tubing, another valve may be activatedthat opens the back end or proximal portion closer to the patient toallow air to be drawn into the system, thus relieving the negativepressure charge that clears the dependent loop.

The system is desirably operable to detect a fully or partially blockedor kinked pneumatic fluid pathway based on an algorithm that considersone or more of elapsed time, pressure differential in the fluid pathway,and predetermined time delay settings. Such blockage may include, or bethe result of the presence of, solids, semi-solids, liquids, gases, orcombinations of the foregoing in the fluid pathway that induce aregistered pressure differential, which actuates the pathway clearingfunction.

The fluid pathway may be a tube, for example, such as a flexible,polymeric material. The fluid pathway may have a single lumen ormultiple lumens. During clearing of the fluid pathway, the accumulator'snegative pressure is used to evacuate at least some or, more preferably,substantially all of the blockage that induced the pressuredifferential, recognizing that the tube will typically have residualmaterial remaining. In one exemplary embodiment, the fluid pathway canbe considered to be “cleared” at the point when the system is able torestore differential pressure to a point below a predetermined pressuredifferential threshold.

When the system detects a dependent fluid loop that generates apredetermined pressure differential (e.g., 10 cmH₂O) between the patientand the canister or collection device, the system can clear thedependent fluid loop. In one embodiment, the system can clear thedependent fluid loop up to half of the patient tubing set length.

The system includes a pressure accumulator to store sub-atmosphericpressure and apply a negative pressure to the fluid pathway downstreamor distal of a blockage that creates a differential across the dependentfluid loop, preferably while substantially maintaining prescribedsub-atmospheric pressure at the patient, and preferably without applyinga positive pressure to the blockage and without using a mechanicalclearing device.

According to a preferred embodiment, the pressure to clear the fluidpathway is created independent of the collection chamber, which providesa space for the collection of fluid, and is then introduced to thecollection chamber. It is believed that such a system is superior to asystem that incrementally applies small pressures to the chamber,checks, and iterates, because such a system may not adequately clear thepatient tube quickly or effectively as the residual pressure in thecollection chamber is transferred to the patient. Also, because airflowis extrapolated from pump work, such a system may require close controlof a vent valve during blockage clearing so it is not interpreted as apatient leak.

Additionally, preferred embodiments of the system do not use positivepressure to unclog a blockage by building up pressure and pumping theclog. Although positive pressure is alternatively used, it isadvantageous according to preferred aspects of the invention to usesub-atmospheric pressure, introduced distally of a blockage, to generatea pressure differential sufficient to “pull” a blockage in a directionaway from the patient. Doing so reduces the risk of exposing the patientto positive pressure and also eliminates the need for mechanisms (e.g.,valves) in the drainage line to prevent such exposure. Also, the use ofsub-atmospheric pressure permits continued measurement of pressure andsubstantially continuous application of sub-atmospheric pressure to thepatient.

The system includes a vent to introduce air into the fluid pathwayupstream or proximal of a blockage to prevent buildup of sub-atmosphericpressure. In other words, the vent provides a vent to relieve thenegative pressure charge across the pressure differential; thereby,moving the fluid. Although it is not its primary function, the vent mayalso prevent buildup of sub-atmospheric pressure in the fluid pathway.Also, relieving the negative pressure charge in sequence is preferablyoptimized such that interruptions or variations of the applied negativepressures to the patient are minimized (e.g., less than suchinterruptions and variations that may be typically caused by manualmanipulation of a tube to move a blockage such as by lifting the tube).

A blockage is cleared within a shortened, predetermined period of time.This feature is beneficial in that it provides a means to quickly clearthe tube while applying less pressure than would be applied by manualmanipulation of the tube to remove a blockage. More specifically, it hasbeen discovered that the use of a source of sub-atmospheric pressurepermits rapid clearing of a tube using moderate pressure differentials.It also permits control of the clearing time and differential pressuremagnitudes.

With reference to the drawings, FIG. 2 illustrates another exemplarychest drainage system 1100 in accordance with aspects of the presentinvention. System 1100 is usable to drain fluid from the pleural and/ormediastinal cavity of a patient. As a general overview, system 1100includes a control module 1200, a collection device 1300, and a fluidpathway 1400. Additional details of chest drainage system 1100 will beprovided herein.

Control module 1200 houses the electronic components of system 1100.Control module 1200 may include any or all of the features describedabove with respect to control module 200. Collection device 1300collects fluid drained from the patient. Collection device 1300 mayinclude any or all of the features described above with respect tocollection device or canister 300.

Fluid pathway 1400 provides a path for fluid from the patient to draininto collection device 1300. Fluid pathway 1400 is configured to extendfrom collection device 1300 to the patient. Fluid pathway has a portion1410 configured to extend proximally toward the patient and a portion1420 configured to extend distally from the patient. As used herein, theterms “proximal portion” and “distal portion” are not limited to anyparticular section or length of the fluid pathway. To the contrary, theterms “proximal portion” and “distal portion” of the fluid pathway arerelative terms meant to describe portions of the fluid pathway that areproximal or distal, respectively, of a fluid pathway portion that maybecome at least partially blocked during use.

Chest drainage system 1100 includes means for substantially clearing ablockage in fluid pathway 1400 that may form between the proximalportion 1410 and the distal portion 1420. The means for substantiallyclearing a blockage in a fluid pathway may include the structures setforth below, and any other known means for substantially clearing ablockage in a fluid pathway. For example, the means can include apositive or negative pressure supply, a source of fluid flow, anapparatus for manipulating the elevation of the fluid pathway, anapparatus for mechanically promoting movement of a blockage (e.g., byradial or axial movement with respect to the fluid pathway), etc.Additional structures and equivalent structures will be apparent tothose of skill in the art.

Control module 1200 includes a pressure source 1210. According to apreferred aspect of this invention, the pressure source 1210 includesmeans for pressure storage. For example, it may include pressure storagethat stores a finite volume of pressurized sub-atmospheric gas asopposed to a continuous or substantially unlimited source of pressure.In other words, such pressure storage can be configured to hold adiscrete “charge” of sub-atmospheric pressure as an alternative to acontinuous or other source of sub-atmospheric pressure that may providea relatively unlimited source of sub-atmospheric pressure. For example,although the pressure source may optionally include hospital wallsuction as a substantially continuous source of sub-atmospheric pressureaccording to aspects of this invention, it is advantageous according toembodiments of this invention to utilize a pressure source including apressure storage configured to store a discrete volume of pressurizedfluid. According to one exemplary embodiment, the pressure sourceincludes an accumulator that is configured to store pressure at leasttemporarily. Additional structures and equivalent structures for storingpressure will be apparent to those of skill in the art from thedescription herein.

Pressure source 1210 is configured to selectively providesub-atmospheric pressure to the distal portion 1420 of the fluid pathway1400. Pressure source 1210 may be operable to provide continuoussustained suction pressure, for example, when system 1100 is notconnected to an external suction source. Alternatively, pressure source1210 may be operable to provide one or more pulses of sub-atmosphericpressure. Pressure source 1210 may provide sub-atmospheric pressure tothe distal portion 1420 of the fluid pathway 1400 via the collectiondevice 1300 and may be coupled directly to collection device 1300.

In an exemplary embodiment, pressure source 1210 comprises a pressureaccumulator 1212 and means for generating sub-atmospheric pressure 1214.Pressure accumulator 1212 is configured to store sub-atmosphericpressure. The stored sub-atmospheric pressure can then be introduced to,or fluidly coupled to, fluid pathway 1400. In an exemplary embodiment,pressure accumulator 1212 is a sealed pressure vessel that ispneumatically connected in circuit with a means for generating pressureand a valve where one side of the valve is connected to the collectiondevice 1300 and the other side of the valve is connected to theaccumulator 1212. This allows the means for generating pressure 1214 tonegatively charge the accumulator to negative pressures (e.g., −700 cmH₂O). When it is configured to store negative pressure orsub-atmospheric pressure, the accumulator may be referred to as anegative accumulator. Also, although the pressure source mayalternatively be the primary source of suction for applyingsub-atmospheric pressure for chest drainage, the pressure sourceaccording to exemplary embodiments of the invention is separate from andsupplemental to the primary source of suction, which may be a wallsuction source that is regulated for applying sub-atmospheric pressureto the drainage line. Accordingly, the accumulator component of thepressure source is, according to exemplary embodiments, a component ofthe pressure source that is distinct from, and/or is operableindependently from, the wall suction source or other primary suctionsource.

Through use of the above-described pressure accumulator 1212 and valvestructure in conjunction with the wall suction, chest drainage system1100 desirably achieves higher volume flows from the patient that may beachieved through conventional drainage systems. In particular, chestdrainage system includes flow paths having low internal resistance andredundant valves to streamline the flow of fluid from the patient. Thismay enable chest drainage system 1100 to achieve flows from the patientas high as 16 liters per minute or more.

The size of the pressure accumulator may be selected based on the emptyvolume of the collection device 1300 and all pneumatic pathways up toand perhaps beyond the point of the distal end of the dependent loop.Desirably, the pressure source 1210 is able to clear a dependent fluidloop in one sequence. Therefore, the size of the pressure accumulatorshould be selected so that it is large enough in size and strength tohold a negative charge that when released into the collection device1300, it temporarily increases the negative pressure in the canister toa level that is able to successfully pull the blockage into thecollection device 1300. For example, if the distance to the top of thecollection device is 50 cm and the length of the fluid pathway 1400allows the blockage to be positioned 20 cm below the collection device1300, then the resulting canister pressure after an accumulator releaseshould be at least approximately −70 cm H₂O in order suck the blockageinto the canister.

Pressure accumulator 1212 may be constructed of plastic (e.g., ABS).Alternatively, pressure accumulator 1212 can be constructed of manydifferent polymers, metals or other suitable materials, as the pressurelevels required for chest drainage are typically not that high. In oneexemplary embodiment, the accumulator 1212 is optionally constructed oftwo or more separate injection molded pieces of plastic and weldedtogether (via ultrasonic welding or other means) in order to ensure thatthe accumulator is a sealed pressure vessel.

Means for generating sub-atmospheric pressure 1214 is operable to chargepressure accumulator 1212, i.e. generate the sub-atmospheric pressurestored in pressure accumulator 1212. Means for generatingsub-atmospheric pressure 1214 may be, for example, a pump or aconnection with an external suction source. Suitable pumps for use aspressure generating means 1214 include, for example, a diaphragm pumpsuch as a diaphragm pump available from Gardner Denver, Inc., ThomasDivision, of Sheboygan, Wis. (e.g., Part No. 1410D/BLDC), although otherdiaphragm pumps and other types of pumps are optionally used. Othermeans for generating sub-atmospheric pressure 1214 will be known to oneof ordinary skill in the art from the description herein. Pressuresource 1210 may further include a sensor 1216 for measuring the pressurestored in pressure accumulator 1212.

It will be understood by one of ordinary skill in the art from thedescription herein that the connection between pressure accumulator 1212and means for generating sub-atmospheric pressure 1214 shown in FIG. 2is illustrative and not limiting. For example, as shown in FIG. 2A,pressure accumulator 1212 and means for generating sub-atmosphericpressure 1214 may be connected in series as opposed to the “T”connection illustrated in FIG. 2.

Control module 1200 also includes a valve 1220 such as a 2-way valve inthe normally closed position. Valve 1220 is in fluid communication withthe proximal portion 1410 of fluid pathway 1400. Valve 1220 mayestablish this fluid communication via a separate vent line 1222. Valve1220 is configured to selectively relieve pressure in the proximalportion 1410 of fluid pathway 1400 by selectively coupling the proximalportion 1410 with open air. Control module 1200 controls the opening andclosing of valve 1220. In operation of system 1100, valve 1220 isnormally closed.

Chest drainage system 1100 also includes means for determining when toactuate the above-described clearing means. The means for determiningwhen to actuate the above-described clearing means may include thestructures set forth below, and any other known means for determiningwhen to actuate the above-described clearing means. For example, themeans can include a controller, a sensor, a timer, or a combination ofthe foregoing. Additional structures and equivalent structures will beapparent to those of skill in the art.

Control module 1200 also includes a differential pressure sensor 1230.Differential pressure sensor 1230 measures a pressure difference betweenthe proximal portion 1410 and the distal portion 1420 of the fluidpathway 1400. To measure the pressure at the proximal portion 1410,sensor 1230 may measure the pressure in vent line 1222. To measure thepressure at the distal portion 1420, sensor 1230 may measure thepressure in collection device 1300. Control module 1200 may use thepressure measured by sensor 1230 to determine when to actuate pressuresource 1210 and valve 1220, as will be described below.

The operation of chest drainage system 1100 will now be described withreference to FIGS. 3A-3E. As chest drainage system 1100 is used to drainfluid from a patient, there is a possibility that the fluid may form acomplete or partial blockage in fluid pathway 1400. The blockage mayinhibit further drainage of fluid from the patient. Accordingly, it isdesirable to promptly remove blockages from fluid pathway 1400.

As shown in FIG. 3A, control module 1200 detects a blockage 1600 influid pathway 1400 using differential pressure sensor 1230. When thereis a blockage 1600 in fluid pathway 1400, a difference in pressure willbe generated between the distal portion 1420 (where suction pressure isapplied) and the proximal portion 1410 (where the suction pressurecannot adequately reach). Accordingly, differential pressure sensor 1230will detect a difference in pressure between proximal portion 1410 anddistal portion 1420 in the event that a blockage 1600 of fluid pathway1400 occurs. Blockage 1600 may generate a difference in pressure assmall as 1 cm H₂O or greater, even less under some circumstances.

For example, a blockage itself may generate a difference in pressure ofany amount from greater than 0 to a greater differential based on thelimits of the system. If for example a column of liquid is 10 cm talland the collection chamber and tube set system only allow a maximum of10 cm height from the bottom-most point of the tubing to the top of thecollection chamber, then the greatest pressure differential would beexpected to be about 10 cm. Alternatively, if a chest drain isapproximately 30 cm tall and the tubing is 72 inch in length, the bottommost portion of the tubing may be 24 inches below the drain, forexample, if the drain is hanging on a hospital bed rail. Therefore,factors such as the maximum differential pressures that can be generatedand the maximum column of fluid that could be collected in the tubewould impact the overall optimization and requirements of an accumulatorprofile (e.g., its volume and charge) in order to be able to remove ablockage in one or more discharges of the accumulator.

For example, and for purposes of illustration only, a −5 cm negativepressure generated in pressure source 1210 may be sufficient to clear a5 cm tube blockage, and a −10 cm negative pressure may be sufficient toclear a 10 cm tube blockage, etc. Such negative pressures can have awide range, including from −5 to −80 cm for example. For example, anaccumulator having a volume of 300 cc may be charged by a pump to anegative −500 cmH₂O. Upon releasing such a charge into a collectioncanister, the residual pressure in the canister achieves a negativepressure that is more negative than the total head height of theblockage (e.g., 14 cm H₂O). This would result in a successful clearingof fluid in the tube. As the fluid clears into the collection chamberthe negative pressure charge of the canister becomes more positive dueto equalization of pressures caused by movement of the blockage;therefore, it is preferable to achieve a residual negative charge in thecanister of at least the height of the blockage, and the system shouldaccommodate for the pressure change as the fluid is cleared in additionto a sufficient excess charge to ensure that the blockage removal ismaximized.

In accordance with aspects of the present invention, control module 1200is programmed to clear the blockage 1600 when the differential pressuremeets or exceeds a predetermined magnitude. When a predeterminedpressure differential is detected between the proximal portion 1410 andthe distal portion 1420 of the fluid pathway, control module 1200 isconfigured to generate sub-atmospheric pressure in pressure source 1210,as shown in FIG. 3B. When a sub-atmospheric pressure having sufficientmagnitude (e.g., a magnitude sufficient to remove a particular blockage)is generated in pressure source 1210, control module 1200 couplespressure source 1210 with the distal portion 1420 of the fluid pathwayvia valve 1244, and opens valve 1220, as shown in FIG. 3C.

The sub-atmospheric pressure from pressure source 1210 then sucks theblockage 1600 in fluid pathway 1400 into collection device 1300, therebyclearing fluid pathway 1400 to continue draining fluid from the patient,as shown in FIG. 3D. The opening of valve 1220 prevents thesub-atmospheric pressure from pressure source 1210 from being applied tothe patient.

When the blockage 1600 is sufficiently drained, control module 1200decouples pressure source 1210 from fluid pathway 1400 using valve 1244,and closes valve 1220, as shown in FIG. 3E. Preferably, control module1200 may be configured to decouple pressure source 1210 when thepressure differential drops below a predetermined point, or after apredetermined period of time.

While control module 1200 is described above as clearing a blockagebased on the differential pressure measured by sensor 1230, it is not solimited. Control module 1200 may be additionally or alternativelyconfigured to clear a blockage or clear the fluid pathway 1400 based onelapsed time of operation of chest drainage system 1100.

Pressure source 1210 provides pressure to collection device 1300 using anetwork of valves 1240, 1242, 1244, 1246, 1248. Valves 1240, 1242, and1246 may desirably be vacuum protection valves. When suction is appliedto fluid pathway 1400 from an external suction source, the suctionpressure is applied via valves 1240, 1242, 1244, 1246. Valve 1248 isnormally closed during operation.

When pressure source 1210 is coupled to fluid pathway 1400, thesub-atmospheric pressure is applied via valves 1244 and 1246. Valves1240 and 1242 remain closed as long as the pressure from pressure source1210 is below (i.e. more negative than) the pressure applied by theexternal suction source. When the pressure from pressure source 1210 isabove (i.e. less negative than) the pressure applied by the externalsuction source, valves 1240 and 1242 reopen, and normal suction pressureis applied to fluid pathway 1400 from the external suction source. Inthis way, even when control module 1200 clears a blockage from fluidpathway 1400, the system 1100 substantially maintains a prescribedpressure at the patient when valve 1220 is opened and pressure source1210 is coupled to fluid pathway 1400. Suitable valves for use as valves1240, 1242, 1244, 1246, or 1248 will be known to one of ordinary skillin the art from the description herein.

Control module 1200 may further include a pressure regulation system1250. Pressure regulation system is operable to regulate the pressureprovided by an external suction source. As shown in FIG. 2, pressureregulation system 1250 may include a check valve 1252, a pressureregulator 1254, and a pressure setting mechanism 1256. Check valve 1252is operable to prevent air from flowing into control module 1200.Pressure regulator 1254 is operable to limit a maximum suction providedby the external suction source. For example, pressure regulator 1254 maylimit suction to a maximum of −40 cm H₂O. Pressure setting mechanism1256 enables a user to vary the applied suction pressure up to a maximumregulated suction value. For example, and for purposes of illustration,the setting mechanism may allow variable adjustment of applied suctionpressure from −1 cm H₂O to a maximum of −40 cmH₂O. The suction pressuremay be any predetermined pressure between 0 and the maximum allowed bypressure regulator 1254. In an exemplary embodiment, pressure settingmechanism 1256 is a mechanical dial. Suitable components for pressureregulation system 1250 will be known to one of ordinary skill in the artfrom the description herein.

As illustrated in FIG. 2, control module 1200 may also include apressure sensor 1258 for sensing the suction pressure provided bypressure regulation system 1250. Control module 1200 may also include anadditional pressure sensor 1260 for sensing a pressure at the output ofcontrol module 1200.

Control module 1200 may also include a high negativity limit valve 1262.In an exemplary embodiment, high negativity limit valve 1262 is aone-way valve that is activated (or opened) when the pressure reaches acertain limit. For example, if high negative pressure exceeds themechanical or electronically predetermined limits of the spring forcesthat keep the high negative limit valve shut, then the valve will openand “relieve” the negative pressure until the pressure is once againunder the mechanical limits where the spring forces would close thevalve shut. This type of valve can be designed in several waysmechanically in order to achieve the effect of opening when certainpressure limits are reached, as would be understood by one of ordinaryskill in the art. For example, the valve optionally includes a springloaded shut off plunger.

Control module 1200 may also include a sealing element 1264. Sealingelement 1264 may be configured to cap, plug, or otherwise partially orfully seal a pneumatic connection between control module 1200 andcollection device 1300. In an exemplary embodiment, collection device1300 is operable to vent out positive pressure through one or more checkvalves when the collection device 1300 is not loaded in the controlmodule 1200. One check valve may be designed to open at very lowpressures. Another check valve may be designed to open at a higherpressure (e.g., >+2.0 cm H₂O). This may be desirable because it allowspositive pressure to be pushed through the control module 1200 and bemeasured by pressure sensors. However, this can only be achieved if thevalve designed to open at very low pressures is plugged when it isloaded into the control module 1200. Accordingly, when collection device1300 is coupled to control module 1200, the low-opening valve coupleswith the sealing element.

Collection device 1300 may also include a shut-off valve 1302. In anexemplary embodiment, shut-off valve 1302 comprises a spring-loadedplunger that seals off the flow paths when the collection device 1300 isnot loaded in the control module 1200. When the collection device 1300is loaded into the control module 1200, the ports of the control module1200 push the spring-loaded plunger, thereby opening the valve 1302 andallowing flow from the collection device 1300 into the control module orvice versa. This specific shut-off valve 1302 provides the flow pathbetween the electronically controlled relief valve 1220 and the reliefflow path to the proximal end 1410 of the fluid pathway 1400.

Collection device may also include a shut-off valve 1304. Shut-off valvemay be configured to seal a connection between control module 1200 andcollection device 1300. In an exemplary embodiment, shut-off valve 1304comprises a shut-off valve similar to that described above with respectto shut-off valve 1302. Shut-off valve 1304 provides the flow path forthe control module 1200 to measure the pressure within collection device1300 as well as allow negatively applied pressure to be applied via anexternal suction source or via pressure source 1210.

Collection device 1300 may also include a vacuum pressure valve 1306,which is described in U.S. Pat. No. 6,358,218, the contents of which arehereby incorporated in their entirety. In an exemplary embodiment,vacuum pressure valve is a one-way check valve, similar to a standardumbrella valve; however, there is no stem, but just a floating discdesign that only allows flow in one direction. The top of the floatingdisc is retained by mechanical features that ensure activation andposition.

Collection device 1300 may also include a self-sealing filter 1308. Inan exemplary embodiment, self-sealing filter 1308 is a gas or liquidpermeable material that seals when exposed to water.

Collection device 1300 may also include a check valve 1310. Check valve1310 is a valve similar to vacuum pressure valve 1306.

Collection device 1300 may also include a means for knock-overprotection 1312. In an exemplary embodiment, knock-over protection means1312 is a nozzle that is suspended in the middle of the collectiondevice volume. By positioning the nozzle in the middle of the collectionchamber volume, it provides a tortuous path for the fluid (e.g., liquidsand/or solids suspended in liquids) to migrate into that exit.Additional structures and equivalent structures for knock-overprotection will be apparent to those of skill in the art from thedescription herein.

Fluid pathway 1400 may also include a distal connector 1402. Distalconnector 1402 connects the body of the fluid pathway 1400 (e.g., adrain tube) to the collection device 1300. Accordingly, distal connector1402 is positioned at an end of the distal portion 1420 of the fluidpathway 1400. Suitable connectors for use as distal connector 1402 willbe known to one of ordinary skill in the art from the descriptionherein.

Fluid pathway 1400 may also include a proximal connector 1404. Proximalconnector 1404 connects the body of the fluid pathway 1400 (e.g., adrain tube) to the patient (e.g., via patient connector 1702 and patientdrain catheter 1700). Accordingly, proximal connector 1404 is positionedat an end of the proximal portion 1410 of the fluid pathway 1400. In anexemplary embodiment, proximal connector 1404 is a needle-less accessconnector. Suitable connectors for use as proximal connector 1404 willbe known to one of ordinary skill in the art from the descriptionherein.

FIG. 4 is a flow chart illustrating an exemplary method 1500 forclearing a fluid pathway in accordance with aspects of the presentinvention. For the purposes of illustration, the steps of the methodwill be described with reference to the components of system 1100.

In step 1502, the differential pressure is checked. In an exemplaryembodiment, control module 1200 checks the differential pressure betweenthe proximal portion 1410 and the distal portion 1420 of the fluidpathway 1400. Desirably, ahead of step 1502, control module 1200 maydetermine an average pressure at each of the proximal portion 1410(e.g., the patient side) and the distal portion 1420 (e.g., the canisterside) over a predetermined period of time. Control module 1200 may thendetermine the difference between these average pressures to obtain thedifferential pressure.

If the differential pressure is less than a predetermined magnitude,method 1500 proceeds to step 1504. If the differential pressure is equalto or greater than a predetermined magnitude, method 1500 proceeds tostep 1506.

In step 1504, the default timer is checked. In an exemplary embodiment,control module 1200 determines how much time has elapsed since fluidpathway 1400 was last flushed. If a predetermined amount of time haselapsed, method 1500 proceeds to step 1506. If not, control module 1200determines that it is not necessary to clear fluid pathway 1400 at thistime, and method 1500 concludes.

In step 1506, the flush hold-off timer is checked. In an exemplaryembodiment, control module 1200 may maintain a flush hold-off timer fordetermining whether a fluid pathway clearance event should be delayed.If the timer has not reached zero, then control module 1200 determinesthat the fluid pathway clearance event should be delayed, and method1500 concludes. If the timer reaches zero, then it is reset, and method1500 proceeds to step 1508.

In step 1508, the accumulator is charged. In an exemplary embodiment,means for generating pressure 1214 generates a sub-atmospheric pressurefor storage in pressure accumulator 1212. When the accumulatedsub-atmospheric pressure reaches a predetermined magnitude (e.g., −40 cmH₂O), the pressure generating means 1214 may be stopped.

In step 1510, the pressure source is coupled for fluid flow to the fluidpathway by opening an accumulator valve. In an exemplary embodiment,control module 1200 couples pressure source 1210 to the distal portion1420 of fluid pathway 1400. Pressure source 1210 may be coupled toprovide pressure directly to collection device 1300.

In step 1512, the vent valve is opened. In an exemplary embodiment,control module 1200 opens valve 1220 to permit release of pressure inthe proximal portion 1410 of fluid pathway 1400.

In step 1514, the blockage is cleared. In an exemplary embodiment,control module 1200 allows the pressure from pressure source 1210 toclear the blockage from fluid pathway 1400. When the sub-atmosphericpressure from pressure source 1210 is depleted, method 1500 advances tostep 1516.

Additionally, control module 1200 may monitor the length of timepressure source 1210 is coupled to the distal portion 1420 of fluidpathway 1400. If pressure source 1210 is coupled to the distal portion1420 for a predetermined length of time, and the sub-atmosphericpressure has not been depleted, then method 1500 advances to step 1516.This may correspond to an event where the blockage is not cleared by thepressure from pressure source 1210.

Still further, control module 1200 may monitor the differential pressurebetween the proximal portion 1410 and the distal portion 1420 of thefluid pathway. If the differential pressure falls below a predeterminedpressure, then it may be determined that the blockage has been cleared,and method 1500 advances to step 1516.

In step 1516, the vent valve is closed. In an exemplary embodiment,control module 1200 closes valve 1220.

In step 1518, the pressure source is decoupled from the fluid pathway.In an exemplary embodiment, control module 1200 decouples pressuresource 1210 from the distal portion 1420 of fluid pathway 1400.

While the above steps are described in an exemplary order, it will beunderstood that the above-described method is not so limited. Forexample, step 1512 may be performed before, after, or simultaneouslywith step 1510. Similarly, step 1518 may be performed before, after, orsimultaneously with step 1516.

The fluid pathway clearing and blockage detection/removal made possibleaccording to aspects of this invention provide substantial benefits.Specifically, there are benefits in terms of at least one of systemoperation, clinical outcomes, and health care cost management.

Regarding operational benefits, the system is optionally configured tooperate automatically to identify and substantially remove tubeblockages that may occur in the drainage line or fluid pathway. Also,the system allows the suction device to keep the fluid pathway moreclear during operation by optimizing fluid evacuation. Additionally, itprovides the ability to apply differential pressure that is not onlyadaptable for each patient, but also for different times for eachpatient according to changes in properties of the fluids removed.Finally, the system detects when the collection device is full and/orblocked. Other operational benefits will be appreciated by those havingskill in this art.

Regarding clinical benefits, the system can help to maximize the abilityfor a patient to expel air, providing an overall improved patientoutcome. It can also help clear any blockage or partial or completeobstruction in the fluid pathway in a shorter duration and reducedmagnitude of applied pressure on a patient as compared with othersystems including the manual raising of a blocked tube. Other clinicalbenefits will be appreciated by those having skill in this art.

Regarding cost benefits, the system makes it possible to benefit fromdecreased cost per treatment of a patient, as well as reduced costs ofthe hospital, insurance company and medical system in general. It canalso help achieve a reduced length of patient stay in the hospital asclinical outcomes are improved. Other cost benefits will be appreciatedby those having skill in this art.

In accordance with other aspects of the present invention, it isdesirable that the collection device be separable from the controlmodule and operates as a gravity-based drain without interrupting thepatient connections. The system may detect whether or not the collectiondevice is loaded in the control module (e.g., when a user changes a fullcanister or uses it temporarily as a gravity-based drain). One canoptionally use gravity whether the canister is in connection with thesystem or not (e.g., by shutting off wall suction or battery power).Also, the system can be configured to apply some suction without havingbattery power.

The system is desirably able to account for when the canister isdisconnected and report that condition to the user of the system. Thesystem can detect whether or not a canister is loaded in the system whena user changes the canister. The system has a means such as a tube clampto prevent air from entering the patient when the canister isdisconnected after use. The user can disconnect the tube set from thecanister, while the canister is loaded in the control module. When acollection device is not loaded and wall suction is detected, thecontrol module may desirably close all possible pneumatic paths in orderto prevent unfiltered air from passing through the control module.

Referring to the drawings, FIGS. 5A-5D illustrate another exemplarychest drainage system 2100 in accordance with aspects of the presentinvention. System 2100 is usable to drain fluid from the pleural cavityof a patient. As a general overview, system 2100 includes a controlmodule 2200, a collection device 2300, and a fluid pathway defined by atube set 2400. Additional details of chest drainage system 2100 will beprovided herein.

Control module 2200 houses the electronic components of system 2100.Control module 2200 may include any or all of the features describedabove with respect to control modules 200 and 1200.

Control module 2200 also includes a reusable body portion 2202 thatincludes ports 2204, 2205, and 2207, among other features. Port 2204 isa vent port configured to releasably couple to a corresponding port 2305on collection device 2300, suction port 2205 is provided for coupling toa source of suction such as wall suction, and suction port 2207 isprovided for coupling to a corresponding port 2306 on collection device2300. Control module 2200 may desirably include a sensor configured todetect whether the collection device 2300 is connected. In an exemplaryembodiment, the sensor is a mechanical switch that is actuated whencollection device 2300 is connected. As is most clearly shown in FIG.5B, the control module 2200 includes a latch 2206 that releasablyretains the collection device 2300 within a recess defined by the bodyof the reusable body portion 2202 of the control module 2200. The latchmechanism 2206 is a mechanical coupling device that engages thecollection device 2300 when it is placed in the recess of the controlmodule 2200. Upon pressing or otherwise moving the latch mechanism 2206,it releases the collection device 2300 for replacement, for ambulation,or for access to collected fluids, for example.

In the illustrated embodiment, the latch 2206 is shown at the top centerof the control module 2200 for engaging a surface on the top portion ofthe collection device. It will be appreciated that the latch 2206 may bepositioned elsewhere or that various forms of mechanical or electricalor magnetic latch mechanisms are alternatively used.

As described previously, ports of the control module 2200 will mate withports of the collection device 2300 when the collection device 2300 islatched to the control module 2200. Accordingly, the drainage systempreferably includes surfaces or components positioned to promotealignment of those ports as they are connected.

Collection device 2300 collects fluid drained from the patient.Collection device 2300 may include any or all of the features describedabove with respect to collection device 300 or 1300. In an exemplaryembodiment, collection device 2300 is a removable and/or replaceablecollection canister that is removably connectable with control module2200. Collection device 2300 includes at least one inlet port 2302 andat least one outlet port 2306. The output port 2306 of collection device2300 is configured to be connected with inlet port 2207 of controlmodule 2200 in order to receive suction pressure from control module2200. Therefore, a suction path is formed that extends from a suctionsource such as wall suction, through port 2205, through port 2207,through port 2306, through port 2302, and into the drainage lumen of thetube set 2400. Also, a vent path or line is formed that extends from thevent port 2204, through the vent port 2305, via a conduit to the ventport 2303, and into a vent lumen of the tube set 2400.

Fluid pathway of tube set 2400 provides a path for fluid from thepatient to drain into collection device 2300. Fluid pathway 2400 isconfigured to connect to inlet port 2302 of collection device 2300, andextend from collection device 2300 to the patient. Fluid pathway 2400may include any or all of the features described above with respect tofluid pathways 400 or 1400.

When coupled, ports of the collection device 2300 are coupled for fluidflow with ports of the control module 2200. Specifically, vent port 2204of control module 2200 is coupled to vent port 2305 of the collectiondevice 2300, and suction port 2207 of control module 2200 is coupled tovent port 2306 of the collection device 2300. Collection device 2300also includes a relief port 2307 for relief of positive pressure withinthe device. Accordingly, as best illustrated in FIG. 5D, the port 2305on collection device 2300 is for a vent line, port 2306 is a suctionport, and port 2307 is a relief valve such as a vacuum protection valve.

Specifically, port 2307 allows patient low pressure venting at arelatively low threshold (e.g., +2 cm H₂O) for primary use when thecanister is disconnected from the control module 2200. When connected,however, the control module 2200 modulates and controls the venting atsuch a threshold (e.g., +2 cm H₂O). However, port 2304 on the top of thecollection device 2300 is a relief valve such as a vacuum protectionvalve that is set as a higher threshold (e.g., +10 cm H₂O), whichprovides additional protection to the patient should, for example, thepower to the system be lost. This feature is beneficial because it helpsto protect the patient when disconnecting the collection device 2300.Also, the collection device 2300 is thus provided with two check valvesat different cracking pressures. When the collection chamber 2300 isloaded into the control module 2200, the check valve port 2307 on theback of the collection device 2300 is blocked with a cap or plug (seeitem 1264 in FIG. 2 for example). This allows the air pressures that are<10 cm H₂O to be monitored and measured by the control module 2200,which is itself able to vent off electronically pressures that are below+10 cm H₂O at any programmed setting (e.g., +2 cm H₂O). When thecollection device 2300 is not loaded in the control module 2200,however, the check valve port 2307 is no longer blocked; thereby,maximizing performance of the system by allowing air to escape atrelatively low cracking pressures.

Collection device 2300 is operable to collect fluid via the fluidpathway 2400 using (i) gravity to draw the fluid through fluid pathway2400 when disconnected from control module 2200 or (ii) suction pressurewhen connected with control module 2200. When collection device 2300 isuncoupled from control module 2200, collection device 2300 is configuredto automatically close and seal its outlet port. This may be desirableto prevent air leakage from the pleural cavity of the patient.Collection device 2300 may be alternated between gravity- andsuction-based fluid collection without interrupting a fluid connectionbetween the patient and the collection device 2300 via the fluid pathway2400. Switching the device between gravity- and suction-based fluidcollection may be performed by connecting or disconnecting collectiondevice 2300 from control module 2200. In other words, when the removableand/or replaceable component is connected, suction can be applied or not(i.e., suction or gravity operation), but when it is disconnected thereis no suction applied. The act of disconnecting the removable and/orreplaceable canister can therefore remove suction if it is being appliedbut would not change from gravity mode when disconnected. In this way,leakage to the patient is avoided.

Additionally, collection device 2300 includes a hanger 2301 coupled to atop surface. Hanger 2301 can be pivoted from a stored position, for whenthe device 2300 is stowed in the module 2200, into an extended positionwhen the device 2300 is separated from the module 2200 for hanging thedevice 2300 from a structure such as a hospital bed rail.

The removable and/or replaceable canister system made possible accordingto aspects of this invention provide substantial benefits. Specifically,there are benefits in terms of at least one of system operation,clinical outcomes, and health care cost management. For example, ithelps to provide meaningful information to health care professionalswhen it is configured to detect and indicate when the patient is and isnot connected to the system. It can also be more sanitary in instanceswith diseased patients (e.g., the ability to have the canisterautomatically close when removed), thus providing a clinical benefit.Finally, it provides an economical solution in that a portion of thesystem is reusable. Generally, there is a significant benefit ofpermitting the canister to alternate between gravity and suction insteadof just either one or the other. Other benefits will be appreciated bythose having skill in this art.

In accordance with aspects of the present invention, a chest drainagesystem may desirably measure and inform the user of patient air leaks.The system may monitor an air leak over time without measuringvolumetric flow rate; instead, it may desirably record the time that apatient has any air leak (e.g., 0 cmH₂O or +2 cmH₂O) duringpredetermined time increments. The system is able to account for whenthe collection device is disconnected and report that condition to theuser of the system. It can optionally report an empty “x” 15 minincrement column or alternatively show some of it. For example, if thecanister is attached 14 out of 15 minutes of an increment, data may beshown. Alternatively, if there is a single second of disconnect in anyincrement, that entire increment can be reported as a disconnect.

The system desirably includes a display for showing the last recordedair leak trend increment in terms of % of time that the patient has anyair leak. The system optionally records the time and/or reports out tothe user the occurrence of an air leak over time. For example, it canreport how many times it flashed Red/“Total Flashes” in a time incrementsuch as 15 min, provide an integral of the waveform for pressureindications over +2 cm H₂O, provide the counted time pressure is over+2, and other indications. The system can therefore record and/ordisplay any inability of a patient to maintain sub-atmospheric pressure,due to a leak in the patient's pleural cavity.

In an exemplary embodiment, the system is configured to measure avariation in the pressure waveform generated by the patient. This isachieved by determining inflection points on the waveform curve.Preferably, the trending display can disregard events such as theactuation of the clearing function. The system displays the air leaktrending history (e.g., over the last 12 hours) in increments (e.g., 15minute increments) and includes an indication when the canister has beendisconnected.

The system displays the last recorded air leak trend increment in termsof % from 0% to 100%. The system can display the air leak trendinghistory of the last 12 hours in 15 minutes increments and it may includewhen the canister has been disconnected. The air leak trend history maybe cleared upon power cycling.

When the control module detects an air leak under gravity (e.g., =>+2.0cmH₂O), it may desirably provide a RED visual notification to the user.When the control module detects an indeterminate air leak under gravity(e.g., between −1 and +2.0 cmH₂O), it may desirably provide a YELLOWvisual notification to the user. And when the control module detects noair leak under gravity (e.g., <=−1 cmH₂O), it may desirably provide aGREEN visual notification to the user.

In an exemplary embodiment, the control module provides a visualnotification to the user when the control module detects a largecontinuous air leak. For example, when the system detects an air leakunder suction (Pressure>Applied Suction Setting Pressure, >equaling lessnegative), it provides a RED visual notification to the user. When thecontrol module detects an indeterminate air leak under suction(Pressure=<Applied Suction Setting Pressure, <equaling more negativeAND>(Applied Suction Pressure)−1 cmH₂O), it provides a YELLOW visualnotification to the user (e.g., applied suction pressure is −20 cmH₂O,and pressure is equal to or less than −20 cmH₂O and more than −21cmH₂O). When the system detects no air leaks under suction(Pressure=<(Applied Suction Setting Pressure) −1 cmH₂O), it provides aGREEN visual notification to the user (e.g., applied suction pressure is−20 cmH2O, and pressure is maintained at equal to or less than −21cmH₂O).

The control module desirably displays the fluctuations of pressureranges in real-time. When activated, the system preferably shows adisplay for a predetermined time interval, e.g., 60 seconds. The systemmay desirably include a service accessible port to enable the user toexport pressure waveform data real-time for data acquisition andrecording. The system may allow for remote or wireless data export.Additionally, the system may use this data export for reporting onsignificant changes in patient condition, such as when no air leak isdetected in the pleural cavity.

Referring to the drawings, FIG. 6 illustrates another exemplary chestdrainage system 3100 in accordance with aspects of the presentinvention. System 3100 is usable to drain fluid from the pleural cavityof a patient. As a general overview, system 3100 includes a controlmodule 3200, a collection device (not shown), and a fluid pathway (notshown). Additional details of chest drainage system 3100 will beprovided herein.

Control module 3200 houses the electronic components of system 3100.Control module 3200 may include any or all of the features describedabove with respect to control modules 200, 1200 and 2200. The collectiondevice collects fluid drained from the patient. The collection devicemay include any or all of the features described above with respect tocollection devices 300, 1300, and 2300. The fluid pathway provides apath for fluid from the patient to drain into the collection device. Thefluid pathway may include any or all of the features described abovewith respect to fluid pathways 400, 1400, and 2400.

Control module 3200 also includes means for detecting the pressurewithin the fluid collection device. The pressure-detecting means may beconfigured to sense the pressure of the collection device when thecollection device is connected with control module 3200. In an exemplaryembodiment, the pressure-detecting means is a pressure sensor. Suitablepressure sensors will be known to one of ordinary skill in the art fromthe description herein. Other equivalent means will be known to those ofskill in this field.

Control module 3200 also includes a display 3202. Display 3202 may beusable to provide a user of system 3100 with any one of a plurality ofvisual notifications. Desirably, display 3202 is configured to displaychanges in the pressure within the fluid collection device. Display 3202may display pressure changes in predetermined increments of time, e.g.,fifteen minute intervals.

In an exemplary embodiment, display 3202 may be configured to indicatewhether and when the collection device is disconnected from controlmodule 3200 during the predetermined time increments. Additionally,display 3202 may be configured to indicate a number of occurrences inwhich the detected fluid collection system pressure exceeds apredetermined minimum magnitude in each of the predetermined timeincrements.

Control module 3200 may be programmed to measure a total amount of airleakage based on the pressure measurements of the pressure-detectingmeans. In this embodiment, display 3202 may be configured to indicate atotal amount of air leakage in a respiratory wave form of the patient,or a duration of an air leak having at least a predetermined minimummagnitude. It may also include a display for indicating collected fluidvolumes.

FIG. 7 illustrates an exemplary display 3202 in accordance with aspectsof the present invention. As shown in FIG. 7, display 3202 includes agraph 3204 for presenting information about a patient air leak to auser. As explained below, graph 3204 may display a trend in occurrencesof changes in pressure of the fluid collection device 3300 over time.This trend may desirably be based on detections of changes in fluidcollection system pressure during predetermined time increments.

The horizontal axis 3206 of graph 3204 represents the time during whichthe patient air leak has been monitored by system 3100. Desirably, thetime may be broken up into predetermined time increments, e.g., 15minute increments. Accordingly, information may be presented to the userabout the patient air leak in 15 minute increments.

The vertical axis 3208 of graph 3204 represents the percentage of timeduring which the patient experiences an air leak. An air leak in thisembodiment may be defined as a predetermined positive pressure, forexample, +2 cmH₂O. For example, point 3210 on graph 3204 shows a pointat which the patient experienced an air leak (e.g., the pressure incollection device 3300 was greater than +2 cmH₂O) for approximately 50%of the predetermined increment of time (e.g., for 7.5 minutes in a 15minute increment of time). Conversely, at point 3212 on graph 3204, thepatient experienced an air leak for only approximately 10% of thepredetermined increment of time (e.g., for 1.5 minutes in a 15 minuteincrement of time).

More specifically, and according to one exemplary embodiment of theinvention, the trending display illustrated in FIG. 7 provides usefulinformation to a clinician or medical practitioner about the status of aparticular patient. Specifically, it indicates an approximate percentageof the time, in sequential time increments, during which the patient isexperiencing an air leak in his or her pleural cavity. This informationis derived from the number of time intervals (e.g., an intervalcorresponding to a respiratory cycle of the patient) during each timeincrement with and without associated air leaks. This is accomplished,for example, by calculating the ratio of the quantity of time intervals(e.g., respiratory cycles (QRC) of the patient) in which there is adetected leak in the time increment (QRC_(leak)) to the total quantityof time intervals (e.g., respiratory cycles of the patient) in that timeincrement (QRC_(total)). Accordingly, the percentage reported in thetrending display is (QRC_(leak)/QRC_(total) (100). For example,QRC_(leak)=50 if the quantity of time intervals in which there is adetected leak is 50 in the subject time increment, QRC_(total)=100 ifthe total quantity of time intervals is 100 in that time increment, andthe ratio QRC_(leak)/QRC_(total) is i 50%. The value 50% would bedisplayed for the subject time increment, indicating to a clinician thatthe patient experienced an air leak for about 50% of the time duringthat time increment.

The preferred display of percentage is beneficial for several reasons.Although the number of air leaks per unit time is optionally displayedas an alternative to percentage, the preferred display of percentage isbelieved to be more significant from the clinical perspective because itindicates the trend of the prevalence of the air leak over time.Additionally, although the magnitude of air leaks is optionallydisplayed as an alternative, the preferred display of percentage isclinically important because it relates to the presence or absence of anair leak over a predetermined magnitude (e.g., +2 cmH₂O) and the trendin that presence/absence.

It will be understood to one of ordinary skill in the art that theexemplary display 3202 shown in FIG. 7 is shown solely for the purposesof illustration, and is not limiting. Other displays may be incorporatedfor presenting information to the user on a patient air leak, as wouldbe understood to one of ordinary skill in the art.

According to one exemplary embodiment, a means is provided for detectinga pressure differential in the fluid collection system. The means fordetecting a pressure differential in the fluid collection system mayinclude a pressure differential sensor. Although the pressuredifferential detecting means could optionally include a bubble detectionchamber, the means for detecting a pressure differential according toexemplary embodiments eliminates the need for bubble detection such asthat provided by the bubble detection chamber disclosed in U.S. Pat. No.7,207,946. This is beneficial in that it enables the use of a “dry”system and can eliminate inconveniences and cost associated with aliquid-filled component that generates bubbles.

According to one exemplary embodiment of the invention, a display isprovided to display a trend in occurrences of changes in pressure of thesystem over time in predetermined time increments based on a number ofdetections of pressure differentials that exceed a predeterminedpressure differential during each of the predetermined time increments,the trend being correlative to the percentage of time that the patientis deemed to have an air leak in the pleural cavity in the predeterminedtime increments. For example, the system is optionally configured todetect pressure differentials that may occur in each breath cycle of apatient. Such pressure differential may or may not reach a predeterminedminimum value (e.g., +2 cm H₂O), but may build until it does exceed thatpredetermined minimum value. When that value is exceeded, the system isoptionally configured to count how many times the value is exceeded in aparticular time interval. This number of times is reported in thedisplay and is considered correlative to the percentage of time that apatient is deemed to have an air leak in the pleural cavity in the timeincrements.

The trend display feature made possible according to aspects of thisinvention provides substantial benefits. Specifically, there arebenefits in terms of at least one of system operation, clinicaloutcomes, and health care cost management. For example, when using thisfeature, a clinician can make more informed patient assessments based onthe trending data (such as the trending data illustrated in FIG. 7). Italso provides an objective indication of the air leak of the patientover time, by providing a predictable, reproducible, explainable, andtranslatable system. More specifically, it makes it possible to indicatethe percentage of the time a patient has an air leak, which may beadvantageous as compared to alternatively providing an indication basedon a magnitude or quantity of fluid being leaked. Additionally, thefluid pathway clearing aspect of the system and the trending displayfunction can operate together as an integrated system. Other benefitswill be appreciated by those having skill in this art.

FIG. 8 is a graph depicting the pressure within the pleural space of apatient in accordance with an aspect of the present invention. Thedisclosed chest drainage system may be configured and used to measurethe pressure within the pleural space without restricting the flow inthe drainage catheter. The rate of decay of the pressure in the pleuralcavity correlates to the assessment of a patient air leak in the pleuralcavity. Accordingly, the disclosed chest drainage system may be used tomonitor an air leak in a pleural cavity of a patient. Monitoring the airleak of the patient's pleural cavity can provide valuable informationregarding treatment and recovery of the patient. This information mayinclude providing the medical staff with increased knowledge andunderstanding on how a post-operative air leak is healing during patientrecovery. This may further lead to establishing reliable data forpattern recognition for multiple patients to assist a doctor or medicalpractitioner in the consideration of when to remove a chest tube. Thisinformation in turn may potentially shorten the length of hospital staya patient may require following thoracic surgery.

Air leaks within the pleural cavity are monitored by measuring the rateof pressure decay in the pleural cavity of a patient, correlating therate of pressure decay to an associated air leak, and generating anindicator showing a trend in the magnitude of the air leak in thepleural cavity. As described above, the rate of exerted pressure decayin the pleural cavity of a patient may be measured using the disclosedchest drainage system.

It has been discovered that the relationship of the trend in air leakresolution is proportional to the measured pressure decay and can beexpressed by the following relationship:

Q _(Airleak) α∫Pdt

where:

i. Q_(Airleak) is an extrapolated air leak,

ii. P is a measured pressure, and

iii. t is time.

Accordingly, the patient air leak correlates to the rate of pressuredecay in the pleural space of the patient.

FIG. 9 is a graph depicting the rate of pressure decay within thepleural space of a patient in accordance with an aspect of the presentinvention. Using the above correlation, the chest drainage system isable to quantify the trend and rate of decay as a function of air leakover differing time intervals. Changes and resolution of the patient airleak as a function of clinical healing are detected by a reduction inthe measured pressure decay rate, and can then be correlated to areduced air leak by the above algorithm.

An indicator can be generated depending on the variation in patient airleak. For example, the change in pressure decay and proportionalcorrelation to air leak variation can be accumulated and the feedbackpresented by a varying trend analysis. The generated indicator mayinclude a simple light means where a reduction in air leak over adetermined period of time correlates to a change in the emitted light.According to one exemplary embodiment, this includes a progressive Redto Yellow to Green light indication. In this embodiment, the progressivechange in the light color provides the clinician with informationrelated to the reduction in the air leak and improvement of the overallpleural health of the patient.

As described previously in connection with FIGS. 6 and 7, the systemmeasures the pressures in the system and detects when the pressuresreach a positive pressure of a predetermined magnitude (e.g., 2cmH₂O).Every time the pressure exceeds this threshold in one embodiment, thesystem records the data and is able to report this out in a trend chartas (Times pressure exceeded Threshold/Time) where time, for example,could be reported in increments such as 15 minute increments.

Another method of quantifying the air leak could include taking recordedpressure waveforms and measuring the area under the pressure waveformthat is above a predetermined threshold. The quantification of air leakrelative to time as a means to provide an objective assessment forpatients is beneficial. Many methods could be used to do so, includingcounting the number of times pressure exceeds a pressure threshold,measuring the duration of time pressure exceeds a pressure threshold,determining an area of a pressure waveform that is above a pressurethreshold, determining the average of the maximum pressures at the timeswhen the pressure exceeds a pressure threshold, for example. Suchquantification in a clinical setting provides an objective assessment ofthe leak integrity of the patient as a measure of patient healingprogression. Having this objective data would, for example, helpclinicians to make decisions that are based on standardized means ofmeasuring air leaks.

When suction is applied, the quantification of air can be captured byseveral means. First, if an air leak is large enough, then undersuction, the system would be able to measure a difference between theintended applied suction and the measured pressure in the collectiondevice or canister. If the measured pressure in the canister is lessnegative than the intended applied suction, then there is presumably anair leak in the patient (assuming that the system is not a collapsiblesystem and that there are no defects in the system).

If the air leak is small, then the system can apply the suction and thentemporarily shut off the source of the suction and seal the negativecharged system (canister, tube set, and pleural space). The system canthen monitor the pressure and look for pressure decay. The system canreport the trend of an air leak and can do so with several methods.

One such method would be to note the times when the system has ameasured difference or a pressure decay under suction and then translatethis to a percentage of time in this state over time (e.g., where timecould be in increments such as 15 min increments). Alternatively,objective quantification of the air leak can be performed by measuringthe area of the pressure differential curve over time in combinationwith the area of the curve of the rate of decay. Since it is preferredto report data as a single data set (e.g., percentage of air leaks overtime, versus percentage of air leaks under gravity over time andpercentage of air leaks under suction), a calibrating constant may befactored in to get optimized percentage air leak trend reporting.

The decay algorithm feature made possible according to aspects of thisinvention provides substantial benefits. For example, for a given unitof time, it may be more preferred to measure pressure decay than tomeasure flow as an indicator of an air leak. Also, it provides anobjective view of the air leak of the patient over time. As an optionalalternative to measuring flow per unit of time, the decay algorithm andthe indicator allow a clinician to tell over a unit of time if a leak issteady, improving, or getting worse. Other benefits will be appreciatedby those having skill in this art.

Another exemplary embodiment, in which a chest drainage system includesa fluid clearing device, is illustrated schematically in FIG. 10. Thefluid clearing device removes fluid or blockages from within a patienttube automatically when a predefined pressure differential existsbetween the measured pressure at the patient (from pressure sensor S3)and the measured pressure within the fluid collector (from pressuresensor S4). Alternatively the fluid clearing device can be activatedbased on a fixed or selectable timer. The fluid-clearing device includesan accumulator and a vacuum pump P1, as illustrated schematically inFIG. 10. When the fluid-clearing device is activated, the accumulatorwill have its air volume drawn down to −600 cmH₂O negative vacuumpressure using vacuum pump P1. A vacuum sensor S1 in line with the fluidcollector may be used to determine the pressure of the accumulator andshut off the pump P1 when the accumulator reaches the desired negativepressure. The fluid-clearing device may also include a microcontrollerfor controlling the activation of the accumulator.

The accumulator may be closed off by a magnetic valve V1 in order tostore the energy (−600 cmH₂O) within the accumulator until the magneticvalve is signaled to activate. Valve V1 may be activated when thedifferential pressure measured between pressure sensor S3 and pressuresensor S4 reaches a predefined differential pressure, at which time thestored energy will be released from the accumulator while simultaneouslyopening a separate vent valve V2 to allow the fluid within the patienttube to flow into the fluid collector. Opening vent valve V2 may allowdifferential pressure to enter at the patient tube, thereby preventingexposure of the patient to high negative pressure. The stored negativepressure from the accumulator will draw the fluid away from the patientand into the fluid collector. Alternatively, the accumulator storedpressure may be adjusted by the algorithm described above, and set pointvalues other than −600 cmH₂O may be utilized as determined to be mostclinically relevant. Additionally, the accumulator stored pressure maybe adjusted based on desired power usable by pump P1 and necessarynegative pressure for removing a blockage.

It may be desirable to clear the patient tube in order to assureaccurate volumetric measurement of the collected fluid by preventingfluid collected within the tube from not being recorded, which maycreate variability in the clinical assessment of the collected drainage.It may also provide clinical benefit by keeping the tube clear so as tofacilitate further drainage and to minimize the backpressure created toa patient trying to expel an air leak. This feature may also minimizecare and effort for the clinical staff.

Vacuum pump P1 may desirably be a diaphragm vacuum pump. The accumulatormay desirably be a 300 cc volumetric vessel accumulator for example.Other volumetric vessel capacities are optionally utilized.

Referring now to FIGS. 11A and 11B, and exemplary tube set 4000 that canbe used in the chest drainage system will now be described. Tube set4000 may include features of tube set 2400 illustrated in FIG. 5B.

As shown in FIGS. 11A and 11B, tube set 4000 includes two lumens 4002and 4004. The first lumen 4002 provides a conduit for draining fluidfrom the patient. The first lumen 4002 includes an outlet port 4006.Fluid drained from the patient may pass through first lumen 4002 and outof outlet port 4006 into the collection device via drain port 2302.Second lumen 4004 provides a conduit for releasing pressure in lumen4002. Second lumen 4004 includes an inlet port 4008 for selectivelycoupling second lumen 4008 to open air. Inlet port 4008 may be connectedto a vent line formed as part of either a collection device or a controlmodule. For example, inlet port 4008 can be connected to port 2303 ofthe collection device 2300. Tube set 4000 may further include astress-relief portion 4010. Stress-relief portion 4010 may be providedadjacent outlet ports 4006 and 4008, as shown in FIG. 11A. Stress-reliefportion 4010 may prevent kinking in tube set 4000 when tube set 4000 isconnected to a corresponding collection device. In an exemplaryembodiment, stress-relief portion 4010 comprises a length of corrugatedtubing.

Tube set 4000 may also include a hose clamp 4012. Hose clamp 4012 may beusable to prevent air from entering the patient when tube set 4000 isdisconnected from the collection device after use. As shown in FIG. 11B,tube set 4000 includes a connecting portion 4014 that connects lumen4002 with lumen 4004. Connecting portion 4014 enables lumen 4004 toselectively release the pressure accumulated in lumen 4002. As shown inFIG. 11B, connecting portion 4014 desirably extends from lumen 4002 inan upstream direction, to prevent fluid drained from the patient fromentering lumen 4004.

Tube set 4000 may also include a sealing element 4016. Sealing element4016 is generally closed but may optionally enable a user of tube set4000 to directly couple lumens 4002 and 4004 with atmosphere. In anexemplary embodiment, sealing element 4016 is a cap or plug that may bemanually inserted or removed or permanently sealed.

Tube set 4000 may also include a needle-less access port 4018.Needle-less access port 4018 may be usable to access and collect thefluid drained from the patient.

Tube set 4000 may also include a catheter connector 4020. Catheterconnector 4020 connects tube set 4000 with a conventional patient draincatheter 4022, which may be inserted in a patient to enable drainage offluid.

According to yet another aspect of this invention, processes areprovided for improved patient therapy. Corresponding systems andalgorithms for carrying out those processes are also provided. Thisaspect of the invention is described with reference to FIGS. 12, 13, and14A-14G.

As background, conventional drainage systems typically set a singlepressure (i.e., set pressure differential or applied vacuum) for theduration of a patient's therapy. For chest drainage, for example, thissingle pressure could be −20 cmH₂O. Such a pressure helps to draw fluid(i.e. air and liquid) out of the chest cavity. As the patient heals,however, there is no longer any fluid in the pleural space.

Alternatively, there may be loculated fluid in the pleural space.Loculated air in the pleural space of a healing patient is likely to beabsorbed by the patient's body. Loculated liquid, however, could becomeinfected. Such loculated liquid and air may be trapped in the pleuralspace of a patient that is very inactive, and the applied pressure fromthe chest drain may have drawn the pleural space together around thecatheter through which fluid is being evacuated, thus essentiallysealing the catheter and preventing the removal of any remaining air andliquid.

It has been discovered, however, that by changing the pressure appliedto the patient, the patient's lung tissue (pleura) can be allowed torelax and move without any or limited patient activity. It has also beendiscovered that controlled pressure changes, or “dynamic pressure,” canprovide significant therapeutic benefit when applied to a patient'spleural space.

According to this aspect of the invention, therefore, a chest drainagesystem is equipped to apply dynamic pressure to a patient's pleuralspace. By applying such dynamic pressure, movement of the patient'sanatomy is caused so as to provide access to and release loculatedliquid and/or air. It has been discovered that this application ofdynamic pressure serves as, in essence, an early means to “ambulate” apatient without the need for the patient to move. Ideally, patients cansense the application of dynamic pressure to their pleural space, thusconfirming the movement of their anatomy and confirming the benefitsconferred by applying a dynamic pressure to the patient.

A chest drain system according to exemplary aspects of this inventioncan be configured to apply dynamic pressure in various ways. Forexample, dynamic pressure may be applied in the form of a brief increasein negative pleural pressure. It can also be applied in the form of abrief decrease in negative pleural pressure to atmospheric pressure.Additionally, it can be applied in the form of a return to prescribednegative pressure after a previous variation in pressure.

It will be understood that the above examples of dynamic pressure arenot intended to be limiting, but are presented for the purposes ofillustration. Other methods are also contemplated for improved patientoutcomes. These would include controlled pressure variations, such as bycomputer algorithms, that may vary pressure according to predeterminedpressure profiles or patterns.

According to one embodiment, patient pressure (i.e., the applied vacuum)is reduced slowly towards atmospheric pressure while no air leak isdetected. Upon detection of an air leak and/or fluid removal, however,the prescribed pressure is then reset. In other embodiments, resettingdoes not occur, as may be the case in which a user activates a mode tonot reset upon detection of an event such as the aforementioned examplesof detection of an air leak and/or fluid removal.

According to another embodiment, an algorithmically controlled pressureprofile is applied rather than a fixed pressure. In this embodiment,pressure will cycle by any selected piecewise linear functions or curvesbetween a maximum prescribed pressure and a minimum prescribed pressure(preferably atmospheric pressure). According to yet another embodiment,a continuous wave pattern (e.g., square, sinusoidal, triangular,saw-tooth, and/or piecewise function, etc.) may be applied. The wavepattern may have a root mean square (RMS) value equal to a prescribedpressure (e.g., amplitude of superimposed waveform variable).

Also, according to still another embodiment, sudden changes inprescribed pressure (e.g., a square wave and/or a pulse) are optionallyemployed to “shock” or “jolt” a patient tissues into movement. Forexample, a specific embodiment would include dropping the pressure(e.g., the degree or amount of applied vacuum) from a prescribedpressure to atmospheric pressure briefly (e.g., for a few seconds) andthen returning to the prescribed pressure.

In one exemplary embodiment, a software algorithm is employed to changethe patient applied pressure over time. The algorithm may be driven by anumber of fixed and/or user-configurable constants. These constantsinclude, for example, a target patient pressure, pattern data/time, anda pattern hold-off time (e.g., 0 seconds for hold-off time would imply asubstantially continuous wave).

Referring to FIG. 12, an exemplary embodiment of a process 5000 forapplying dynamic pressure is illustrated. Specifically, FIG. 12illustrates a process and logic for applying dynamic pressure to apatient.

At the outset of process 5000, a user configures patient settings atSELECT DYNAMIC PATTERN. The chest drainage system then applies a targetpressure to the patient at SET TARGET PATIENT PRESSURE. The chestdrainage system then waits for a pattern hold-off time to expire atPATTERN HOLD-OFF EXPIRED (e.g., 0 seconds means that a continuouswaveform is being used). If the pattern hold-off time has not expired, adelay such as a time delay of one second is introduced at DELAY 1 SEC.

If the pattern hold-off time has expired, a loop starts to index out thepattern buffer data. Specifically, a data point (whether a positivevalue or a negative value) is retrieved from a pattern data buffer atLOAD PATTERN BUFFER TIME INDEXED PRESSURE OFFSET VALUE. The data pointis then added to the target patient pressure at ADD PRESSURE OFFSET TOTARGET PRESSURE & APPLY TO PATIENT. When the data point is added to thetarget patient pressure, a bipolar waveform can be achieved around thetarget pressure, for example, if desired. The loop is repeated if moredata is left in the buffer at DATA LEFT IN PATTERN BUFFER, and a onesecond delay is introduced at DELAY 1 SEC. If no more data is left inthe buffer at DATA LEFT IN PATTERN BUFFER, then the pressure applied bythe system is returned to the target patient pressure.

A preferred embodiment of a system having this dynamic pressure featurewill accept any arbitrary or pre-determined waveform. Alternatively,this data can be based upon a formula. For example, the electroniccontrol module (ECM), which can be a drain controller such as controlmodule 1200, may change the waveform buffer pointer from one to anotherbased upon user desire or automatically with detected changes in patientstatus. It can also be used in combination with a decreasing pressurealgorithm described below such that the waveform is applied (and scaled)based upon the difference between a target patient pressure and acurrent patient pressure due to healing status.

According to one exemplary embodiment, the dynamic pressure featureincludes a decreasing pressure regimen. For example, if the dynamicpressure is controlled using a software algorithm, the algorithm will bedriven by a number of fixed and/or user-configurable constants. Theseconstants include, for example, an initial patient pressure, an fluiddrainage hold time, and a percentage reduction. The percentage reductioncan have any value, but an exemplary embodiment has a range of 5% to100%.

Referring to FIG. 13, an exemplary embodiment of a process 6000 forapplying decreasing dynamic pressure is illustrated. Specifically, FIG.13 illustrates a process and logic for applying decreasing dynamicpressure to a patient.

At the outset of process 6000, a user configures patient settings at SETPROFILE PARAMETERS. The chest drainage system then applies a targetpressure to the patient at SET APPLIED PATIENT PRESSURE TO TARGETPRESSURE. The chest drainage system then waits for a delay time toexpire at DELAY HOLD TIME. The system then monitors for fluid drainageat FLUID LEAK DETECTED. If yes, the system loops back to SET APPLIEDPATIENT PRESSURE TO TARGET PRESSURE. If/fluid drainage is not sensed,and no drainage is detected for a drainage hold time period, the appliedpatient pressure is reduced by a % reduction of the initial pressurevalue at DECREASE PATIENT PRESSURE BY % OF TARGET PRESSURE OF STOP ATATM PRESSURE.

The system can be configured to jump back to the initial patientpressure on the first occurrence of leak detection. Optionally, ifdrainage is detected, the system will increase the applied pressure bythe amount last dropped (the last % reduction) until the initial patientpressure is resumed.

When the patient is fully healed and enough time has passed, the appliedpressure of the chest drainage system is preferably set to 0 cmH₂O. Ifso the system can loop back to DELAY HOLD TIME as illustrated in FIG.13.

Although reference is made to a percentage change in pressure, it iscontemplated that the magnitude of any change may be measured indifferent ways and may also vary as opposed to being constant. Forexample, the pressure may be decreased by any amount. This decrease (orincrease or other change) can be dynamic as well or fixed in naturedepending upon a desired “reduction” profile. Additionally, appliedpressure is optionally decreased faster at the start and more slowlytowards the end or vice versa. The change in pressure is optionally apercentage of the current target rather than the prescribed target togenerate a different profile such as an asymptotic profile towards afinal pressure.

As noted previously, a wide variety of dynamic pressure changes orpatterns are optionally employed by the chest drainage system. Suchchanges can include cyclical, periodic, random, repeated or one-timechanges, or combinations of patterns or changes. They can also includerepeating or random patterns or cycles of constant or changing duration.In other words, the dynamic pressure changes or patterns can be selectedfrom a variety of options depending on the type of patient, a patient'scondition, the preference of the user of the chest drainage system, andother variables. They may also have a wide variety of amplitudesdepending on those and other factors. Finally, they may be designed by auser of the chest drainage system and input into the chest drainagesystem to match a user's preference.

Referring to FIGS. 14A-14G, several exemplary dynamic pressure changesor patterns are shown for purposes of illustration. For example, thedynamic pressure change or pattern is optionally:

a bipolar pulse such as that shown in FIG. 14A, which ranges between 0cmH₂O and −120 cmH₂O to interrupt a substantially constant appliedpressure of −20 cmH₂O;

a pulsed sine wave such as that shown in FIG. 14B, which ranges between−10 cmH₂O and −30 cmH₂O to interrupt a substantially constant appliedpressure of −20 cmH₂O;

a substantially continuous sine wave such as that shown in FIG. 14C,which ranges between −10 cmH₂O and −30 cmH₂O;

a repeating square wave such as that shown in FIG. 14D, which rangesbetween −10 cmH₂O and −30 cmH₂O;

a bipolar pulse such as that shown in FIG. 14E, which ranges between 0cmH₂O and −40 cmH₂O to interrupt a substantially constant appliedpressure of −20 cmH₂O; and

a decreasing pressure pattern (with an air leak reset) such as thatshown in FIG. 14F (without reset override) and 14G (with resetoverride), which steps from −20 cmH₂O to 0 cmH₂O to interrupt asubstantially constant applied pressure of −20 cmH₂O.

The delivery of dynamic pressure regimens to patients is performed usinga chest drainage system according to aspects of this invention. Forexample, the moderated or controlled pressure can be increased using acontroller such as control module 1200. The controller can actuate aninternal vacuum pump such as vacuum pump P1 illustrated schematically inFIG. 10. Alternatively, the applied pressure can be pulsed with anaccumulator such as accumulator 1212. Additionally, pressure (e.g., theapplied vacuum) can be decreased towards atmospheric pressure by openinga vent valve such as vent valve V2. These and other mechanisms of thechest drainage systems disclosed herein are used to adjust patientapplied pressure.

In summary, the dynamic pressure aspect of the present inventionprovides a drainage system for removing air and liquids by a processincluding, according to one embodiment, setting target patient appliedpressure (e.g., an applied vacuum) and superimposing an arbitrary orother waveform or pattern of pressure upon the patient applied pressuresetting at a set interval. The interval may be zero or continuous, andthe pattern may be a waveform or pattern such as square wave, a sinewave, a triangular wave, a saw-tooth wave, bipolar, unipolar, or awaveform or pattern that is changed upon user selection. Alternatively,the waveform is optionally (i) changed automatically based upon detectedcondition such as patient status (ii) changed upon user selection, or(iii) combinations of (i) and (ii). Also, the set interval is optionallyselected based upon user demand or upon patient status.

If decreasing dynamic pressure is employed, one exemplary processincludes setting a target patient applied pressure, considering(including for example interrogating for) a patient's status and/orhealth, and decreasing patient pressure towards atmospheric pressure byset pressure intervals at set time intervals. If patient status changes,pressure optionally returns to a target pressure, and in otherinstances, may be configured to not return to the target pressure. Also,the direction of pressure change is optionally based upon patient statusand/or health. The pressure is optionally bounded by and upper and lowervalues, and decreasing dynamic pressure is optionally superimposed upontop of target patient pressure.

Additionally, an increasing pressure regimen is optionally included inthe chest drainage method. Such a regimen can be utilized to account forfluctuations in a patient's air leak. For example, a patient could behealing with any leak gradually diminishing over time, but then the leakcould get worse. Also, then the patient could return again towards ahealing condition where the leak is again gradually diminishing.Accordingly, an increasing pressure regimen is optionally included.

The exemplary chest drainage systems and methods disclosed hereinprovide advantages, as set forth previously. The chest drainage systemsdescribed herein produce superior patient outcomes, improve ease of useand objectivity for the clinical decision making process, and maintain ahigh level of robustness and reliability.

Also, the systems and methods described herein can help health careprofessionals to determine one or more of the following: the amount offluid that is being evacuated from a patient; the rate at which thefluid is being evacuated; the presence of an air leak in the pleuralspaces of a patient's lungs; whether and when the patient needs suction;when a drainage tube can be pulled; and whether the pleural spaces areinfected or not. Finally, the chest drainage systems described hereinare environmentally friendly, affordable, mobile, and easy to use withminimal setup and disposal.

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather, various modifications may be madein the details within the scope and range of equivalents of the claimsand without departing from the invention. For example, while at leastsome of the embodiments disclosed herein are applicable to apply and beused with human patients, all of the disclosed embodiments may equallyapply to (i) non-human mammals, as well as (ii) systems that mimic thefunctioning of human patients, but that are not actually human patients,including but not limited to practice mannequins and/or patientsimulators.

1. A chest drainage system including: a collection device; a fluidpathway configured to extend from the collection device to a patient;and a pressure source configured to selectively provide sub-atmosphericpressure to the fluid pathway; wherein the system is configured tointroduce the sub-atmospheric pressure from the pressure source at asubstantially constant target pressure and at a dynamic pressure thatvaries from the target pressure.
 2. The chest drainage system of claim1, wherein the constant target pressure is selected for the patient. 3.The chest drainage system of claim 1, wherein the chest drainage systemhas a target pressure is −20 cm H₂O.
 4. The chest drainage systemaccording to claim 1, wherein the chest drain system comprises acontroller configured to maintain the target pressure and apply thedynamic pressure.
 5. The chest drainage system according to claim 1,wherein the chest drainage system comprises an internal vacuum pumpconfigured to adjust the sub-atmospheric pressure.
 6. The chest drainagesystem according to claim 1, wherein the chest drainage system comprisesan accumulator configured to adjust the sub-atmospheric pressure.
 7. Thechest drainage system according to claim 1, wherein the chest drainagesystem comprises a vent valve configured to adjust the sub-atmosphericpressure.
 8. The chest drainage system according to claim 1, wherein thechest drainage system is configured to apply dynamic pressure bychanging the pressure applied to the patient such that the patient'spleura moves without any or limited patient activity.
 9. The chestdrainage system according to claim 1, wherein the chest drainage systemcomprises a controller programmed with a computer algorithm that variesthe sub-atmospheric pressure according to a predetermined pressureprofile or pattern.
 10. The chest drainage system of claim 1, furthercomprising: a controller programmed with a computer algorithm thatvaries the sub-atmospheric pressure according to a predeterminedpressure profile or pattern; wherein the system is configured to applydynamic pressure by changing the sub-atmospheric pressure applied to thepatient such that the patient's pleura moves without any or limitedpatient activity.
 11. (canceled)
 12. A method for draining a pleuralcavity of a patient, the method comprising: applying dynamic pressure tothe pleural cavity by changing sub-atmospheric pressure applied to thepatient such that the patient's pleura moves without any or limitedpatient activity, thus facilitating removal of loculated fluid from thepleural cavity.
 13. The method of claim 12, wherein a negative pressurescheme or setting is prescribed.
 14. The method of any of claim 12wherein the step of applying dynamic pressure comprises a decreasingpressure regimen.
 15. The method of claim 12, the method comprising:applying (i) a brief increase in negative pleural pressure, (ii) a briefdecrease in negative pleural pressure to atmospheric pressure, and/or(iii) a return to the prescribed negative pressure after a previousvariation in pressure.
 16. The method of claim 12, further comprising:controlling dynamic pressure using a computer algorithm and varyingpressure according to a predetermined pressure profile or pattern. 17.The method of claim 12, further comprising: reducing patient pressureslowly toward atmospheric pressure when no air leak is detected.
 18. Themethod of claim 13, further comprising: resetting patient pressure tothe prescribed negative pressure upon detection of an air leak and/orfluid removal.
 19. The method of claim 12, further comprising:establishing additional sub-atmospheric pressure to the pleural cavityupon detection of an air leak and/or fluid removal as detected by achest drainage system, wherein the chest drainage system comprises acollection device configured to (i) detect air leakage and/or (ii) fluidreceived in (a) the collection device or (b) any tubing or conduit influid communication between the collection device and the pleural cavityof the patient.
 20. The method of claim 13, further comprising: varyingpressure according to a continuous wave pattern with a root mean squarevalue equal to the prescribed negative pressure.
 21. The method of claim12, further comprising: varying pressure to include sudden changes inthe prescribed negative pressure.
 22. The method of claim 12, furthercomprising: configuring patient settings; applying a target pressure tothe pleural cavity of the patient; applying a dynamic pressure in awaveform around the target pressure; and returning the pressure appliedby the system to the target pressure.
 23. The method of claim 12,further comprising: operating an algorithm based on inputs including atleast one of an initial patient pressure, a fluid drainage hold time,and a percentage reduction; applying a target pressure to the patient;monitoring for fluid drainage; and reducing applied patient pressure bya percentage reduction of the target pressure if no fluid drainage isdetected.
 24. The method according to claim 12, wherein the dynamicpressure comprises at least one of the following changes or patterns: abipolar pulse that interrupts a substantially constant applied pressure;a pulsed sine wave that interrupts a substantially constant appliedpressure; a substantially continuous sine wave; a repeating square wave;and a decreasing pressure pattern that interrupts a substantiallyconstant applied pressure.
 25. The method according to claim 12, furthercomprising: setting target patient applied pressure and superimposing awaveform or pattern of pressure upon the patient applied pressuresetting, the waveform or pattern including at least one of (i) a squarewave, (ii) a sine wave, (iii) a triangular wave, (iv) a saw-tooth wave,(v) a bipolar pattern, (vi) a unipolar pattern, (vii) a waveform, (viii)any permutation of the foregoing waveform or patters (i) through (viii),(ix) a pattern that is changed upon user selection, or (x) a waveform orpattern optionally changed automatically based upon detected patientstatus.
 26. The method according to claim 12, further comprising:setting a target patient applied pressure; monitoring for fluiddrainage; decreasing patient applied pressure toward atmosphericpressure by set pressure intervals at set time intervals; and optionallyreturning pressure to the target patient applied pressure.
 27. Themethod of claim 26, wherein the step of returning pressure to the targetpatient applied pressure occurs.
 28. The method according to claim 12,further comprising: setting a target patient applied pressure;monitoring for fluid drainage; decreasing patient applied pressuretoward atmospheric pressure by set pressure intervals at set timeintervals; and maintaining the pressure at the target patient appliedpressure irrespective of any detection of fluid drainage occurringresulting from the step of monitoring for fluid drainage.
 29. A chestdrainage system comprising: a collection device; a fluid pathwayconfigured to extend from the collection device to a patient andestablish fluidic communication with the patient's pleural space; and apressure source capable of being adjusted to provide sub-atmosphericpressure to the fluid pathway; wherein pressure of the fluid pathway ismanaged (i) during a first period to be at or within a predeterminedsub-atmospheric target pressure or target pressure range, and (ii)during a second period at least intermittently outside of the firstsub-atmospheric pressure range.
 30. The chest drainage system of claim29, wherein the pressure of the fluid pathway is managed to enhanceremoval of any loculated fluid from the pleural space of the patient byintermittently changing the pressure applied to the pleural space. 31.The chest drainage system of claim 29, wherein the system is configuredto enhance removal of any loculated fluid from the pleural space of thepatient by intermittently changing pressure applied to the pleural spaceto sub-atmospheric pressure values that are outside of a target range ofsub-atmospheric pressure values.
 32. The chest drainage system of claim29, wherein the pressure of the fluid pathway is managed to decreaseapplied suction in the pleural space of the patient by reducing theapplied pressure.
 33. The chest drainage system of claim 29, wherein thechest drainage system is configured to re-establish applied suction upondetection of a leak.
 34. The chest drainage system of claim 29, whereinthe chest drainage system is configured (i) not re-establish appliedsuction upon or resulting from detection of a leak, and/or (ii) bypassor override via a user input or user configurable setting anyconfiguration that otherwise would re-establish applied suction upondetection of a leak.